Answer:
B ) 1.5 m/s
Step-by-step explanation:
For the apparent frequency reflected by enemy submarine , the Doppler effect formula is
F = F₀ ( V + v) / (V - v)
F anf F₀ are real and apparent frequency , V and v are velocity of sound and velocity of enemy submarine respectively.
ΔF / F₀ =

Put ΔF = 200; F₀ = 100000 and V = 1482
200 / 100000 =

v = 1.5 m s⁻¹ .