Average velocity is given as the total displacement of an object over a given time interval
Average velocity = total displacement /time interval
consider the time interval t₁ = 0 to t₂ = 4
at t₁ = 0 , d₁ = 0 km
at t₂ = 4 , d₂ = 300 km
Δd = total displacement = d₂ - d₁ = 300 - 0 = 300 km
Δt = time interval = t₂ - t₁ = 4 - 0 = 4 h
average velocity is given as
V = Δd/Δt = 300/4 = 75 km/h
Hence the correct choice is
C) 75 km/hr