Answer:
B) 0.0073 mm/s
Step-by-step explanation:
The rate of change of area is the product of the circumference and the rate of change of radius:
dA/dt = C·dr/dt
dr/dt = (dA/dt)/C
Of course, C = 2πr, so ...
dr/dt = (7 mm²/s)(2π·152 mm) ≈ 7/955.04 mm/s ≈ 0.0073 mm/s
