The correct answer is (a) VT=\(\frac{V_e}{\sqrt{\sigma}}\)
To explain: The relation between true air speed and equivalent air speed is VT=\(\frac{V_e}{\sqrt{\sigma}}\) where VT is true air speed, Ve is equivalent air speed and σ is a constant.The true air speed have to be converted into equivalent airspeed before multiplication to derive the drag power equation.