1. A horizontal shrink is a result of changing the period of the function. The answer is
a. cos (x/5)
2. A vertical stretch is a result of changing the amplitude. The answer is
d. -5 cos (x)
3. Opposite to number 1, the answer is
c. cos (7x)
4. Opposite to number 2, the answer is
b. 2/3 cos (x)