Grammar

Jaw is a noun referring to the lower part of the face that covers the teeth and helps in eating and speaking. It names a specific body part rather than describing an action or quality, making noun the clear correct choice.

Jig is primarily a noun referring to a lively dance or a device/tool used to guide cutting. While it can function as a verb meaning to dance a jig, its most common meaning names something (a dance or tool). Option B is correct.

Juxtapose is a verb meaning to place different things together for a contrasting effect. It describes an action of positioning elements side by side for comparison, making verb the correct classification.

Obese describes a physical condition of being significantly overweight. It functions as an adjective because it modifies nouns (e.g., 'obese person,' 'obese patients'). Adjectives describe qualities or states, and 'obese' characterizes a person's body type, not an action or thing.

Abjure is a verb meaning to solemnly renounce, reject, or give up a belief, opinion, or former practice. It describes an action taken by someone, such as abjuring heresy or abjuring allegiance. Verbs express actions or states, and 'abjure' fits this category perfectly.

Object is most commonly a noun referring to a material thing that can be seen or touched (e.g., physical object). While 'object' can also be a verb meaning to oppose or disagree, its primary and most frequent usage is as a noun naming a thing or entity.

Oblique is an adjective meaning neither parallel nor perpendicular, slanting, or indirect. It describes the geometric or conceptual relationship between things (e.g., 'oblique angle,' 'oblique reference'). Adjectives modify nouns by describing their qualities or orientations.

Obnoxious is an adjective describing something extremely unpleasant, annoying, or objectionable. It characterizes the quality of a person, behavior, or thing (e.g., 'obnoxious behavior,' 'obnoxious smell'). Adjectives serve to describe attributes, and 'obnoxious' serves this descriptive function.

Obsequies is a noun (plural form) referring to funeral rites or ceremonies. It names specific ceremonial practices performed for the dead. Nouns name people, places, things, or concepts, and 'obsequies' fits this category as it names a type of ceremony.

Observe is a verb meaning to notice, watch, or perceive something, or to comply with a rule or custom. It describes the action of seeing or following (e.g., 'observe the stars,' 'observe traditions'). Verbs express actions, and 'observe' fits this pattern perfectly.

Obscene is an adjective describing something offensive, disgusting, or morally repulsive, especially in a sexual context. It characterizes the quality of something (e.g., 'obscene language,' 'obscene gesture'). Adjectives describe attributes, and 'obscene' serves this descriptive function.

Obscure is an adjective meaning not discovered or known about, uncertain, or unclear. It describes the state of something (e.g., 'obcure origin,' 'obscure writer'). While 'obscure' can also be a verb meaning to hide, its adjectival use is common in describing lack of clarity or fame.

Oblong is an adjective describing an elongated shape, object, or figure with rounded corners. It modifies nouns by describing their geometric form (e.g., 'oblong table,' 'oblong face'). Adjectives describe qualities like shape, size, or appearance.

Obsess is a verb meaning to dominate or preoccupy someone's thoughts excessively. It describes the mental action of constantly thinking about something (e.g., 'obsess over details'). Verbs express actions or states of mind, and 'obsess' represents an ongoing mental preoccupation.

Obsequious is an adjective describing someone who is excessively obedient or attentive to gain favor, often in a servile way. It characterizes a person's behavior or attitude (e.g., 'obsequious manner,' 'obsequious servant'). Adjectives describe behavioral qualities.