Verbal Analogies

A traitor is someone who lacks loyalty (opposite). Similarly, a liar is someone who lacks truthfulness (opposite). Both pairs represent a virtue and the person characterized by its opposite.

Island is surrounded by water. Similarly, oasis is surrounded by desert.

Editor works for newspaper (profession:workplace/medium). Lecturer:university, teacher:school, nurse:hospital all follow this. Architect:design breaks the pattern - design is what an architect creates, not where they work (it should be architect:firm or construction site).

Amplify argument, redouble efforts, maximise profits, enhance power all represent making something stronger/better. Exacerbate sales breaks the pattern - exacerbate means to make a negative situation worse, but sales are neutral or positive to increase. The relationship is semantically inconsistent.

The pattern is object:sound (birds-chirp, paper-crinkle, silk-rustle). Aeroplane:drone fits this (aircraft make droning sounds). Elephant:tusk breaks the pattern - tusk is a body part, not a sound.

Here, both the given word are synonyms.

Handcuffs constrain a prisoner and leash constrains a dog. 

Room is part of a house (part:whole). Cockpit is part of a plane (part:whole). The other options don't show this relationship - chair:room is furniture:space, cabinet:ship is unclear (not essential), wheel:car is component:vehicle but not a compartment.

The relationship between 'sorrow' and 'death' is that sorrow is the emotional response or feeling caused by death. Similarly, 'happiness' is the emotional response caused by 'birth'. Both pairs represent an emotion caused by a significant life event - one negative (death causing sorrow) and one positive (birth causing happiness).

A SINGER is part of a CHORUS (a group of singers). Similarly, an ARTIST is part of a TROUPE (a group of performers). In both cases, an individual performer belongs to a collective performing group.

 The association is based on the animal and how it moves. A bear lumbers as it moves. Lumber in this fashion means to move in a slow and slightly clumsy manner. With this in mind, cat-stealth is the best option because cats move in a stealthy manner. 

The relationship is 'specific organism : its biological class'. A termite is a type of insect, just as a lizard is a type of reptile. Both pairs show an instance followed by its broader taxonomic category.