Pick four random integers from 1 to 9, A, B, C, D. They are used in both Q4 and Q5. 4. The height of a delivery drone h(t), in meters, is given by: 1 h(t) = ( At + t 100 - t + 1000D), where t is time in seconds since 9:00:00 am. For simplicity, it is fine to have a negative time or a negative height. (a) Find out h'(2). What does it mean in this context? (b) When does the drone have a downward acceleration of 9.81 m/s? Show process. (c) [50 words limit] Around the moment the drone reaches a maximum velocity, what happens to the positive/negative sign of h"(t)? For example, does h"(t) stay positive? (tip: You learned this in MHF4U: How would h'(t) behave around the time the drone reaches a maximum height?)