Answer:
B - to convince the West to invest in the Soviet Union
Explanation:
Cementing his legitimacy.
Had Khrushchev not denounced Stalin, he would have had to compete with his legacy. This would have been hard to do, Stalin’s reign saw the country rise from an agrarian backwater wracked by civil war to an industrial powerhouse that won in the Great Patriotic war and developed the atom bomb.
However, if the emphasis were placed on the negative aspects of Stalin’s reign, purges, GULAG system, then Khrushchev would have a relatively free hand to break with Stalin’s projects, such as the agricultural climate optimization. On the other hand, he would not be obliged to compete with Stalin in ability, where he would be unlikely to come out ahead.
There was also the matter of the murder/execution of Beria, Stalin’s right hand man. Khrushchev led a palace coup to neutralize Beria and take power. If Stalin, and by extension Beria were turned into monsters, its unlikely that anyone would look into Beria’s dubious arrest and execution and use it as a pretext for their own coup.