Q.[ILLEGIBLE — page defect: the question stem is lost at the top-of-page scan boundary/blot]

The stem of this question is lost at the top-of-page scan boundary/blot, and options (a) and (b) are also illegible; only options (c) −ab² and (d) ab survive, which is not enough to work out or verify the intended answer.

Note on the source scan: the question stem is obscured by a page defect at the top-of-page scan boundary/blot, so the actual quantity being asked for is unknown. Only options (c) −ab² and (d) ab are legible. Based on its position on the paper (between the Integrals and Differential Equations questions), it is placed near where an Application-of-Integrals …