The minimum velocity (in $\mathrm{ms}^{-1}$ ) with which a car driver must traverse a flat curve of radius $150 \mathrm{~m}$ and coefficient of friction $0.6$ to avoid skidding is
(a) $60 \mathrm{~ms}^{-1}$
(b) $30 \mathrm{~ms}^{-1}$
(c) $15 \mathrm{~ms}^{-1}$
(d) $25 \mathrm{~ms}^{-1}$