Answer:
C) less than 5 times as much as your grandfather in terms of real income
Explanation:
Because the prices have risen since 1961 the purchasing power of a single dollar in 1961 greater than one dollar t present day.
So in real income terms, the difference is not 5 times, the difference is lower.
Also, if the inflation rate was high enough, your grandfather could be winning more in 1961 than you today.