Answer:
a. 9.1 percent deflation between the first and second years, and 4 percent deflation between the second and third years.
Step-by-step explanation:
To calculate the rate of inflation/deflation, we have to divide by the oldest price index.
The second year, the variation of the price index was:

This means a 9.1% deflation.
The third year, the variation of the price index was:

This means a 4% deflation.