Answer must be D) Loop Jamming
Let us examine each option:
A) Loop unrolling: The number of jumps can be reduced by replicating the body of the loop if the number of iterations is found to be constant (that is, the number of iterations is known at compile time).
If body of loop is big, unrolling is not favorable.
B) Strength reduction: Replacing an expensive operation with an equivalent cheaper operation is called strength reduction. For example, the * operator can be replaced by a lower strength operator +.