Directions: Four parts of the sentences given below have been underlined. Identify the part having an error. If no part has an error, mark (E).

Underlying aerodynamics and (A) all other (B) branches of theoretical mechanics (C) are the laws of (D) motions developed in the seventeenth century. (E) No error

'Underlying' is a singular adjective form, and the noun it modifies is 'aerodynamics' (singular field). The verb should be 'is' not 'are'. Additionally, 'motions' should be 'motion' to match the singular subject 'laws'. The correct sentence is 'Underlying aerodynamics and all other branches of theoretical mechanics IS the laws of MOTION developed in the seventeenth century.' There are actually two errors, but the most critical one is in part D with 'motions' being incorrect.