What is the indirect object in the following sentence?
the mother wasp digs the tarantula a grave.
a. wasp
b. digs
c. tarantula
d. grave

D. grave

As for this problem together with the options presented with it, the most probable answer and the most likely one to be the correct answer is C. Who

Whose would be referring to be asking as to the ownership of an object or something. Whom, on the other hand, would be more on the person directed to or to who should the action be done to. Who, in this case, would act as someone who would do the act itself.

The third answer is correct.