i think its b
Step-by-step explanation:
Answer:
B: (2,[infinity]]
Step-by-step explanation:
because you will take all numbers bigger than 2 but 2 is not included
The function for the height is

f(0) = 5 cos(0) + 7 = 5 + 7 = 12 (verified)
The period is T = 12 hours.
After 4 hours (t = 4), the height is

A graph of f(t) confirms the answer.
Answer: 4.5 ft