A clock tower stands at the crossing of two roads which point in the north-south and the east-west directions. P, Q, R and S are points on the roads due north, east, south and west respectively, where the angles of elevation of the top of the tower are respectively, α, β, γ and δ. Then $(\frac{PQ}{RS})^2$ is equal to:

$\frac{cot^2 α+cot^2 β}{cot^2 γ+cot^2 δ}$ $\frac{cot^2 α+cot^2 δ}{cot^2 β+cot^2 γ}$ $\frac{tan^2 α+tan^2 δ}{tan^2 β+tan^2 γ}$ $\frac{tan^2 α+tan^2 β}{tan^2 γ+tan^2 δ}$

$\frac{cot^2 α+cot^2 β}{cot^2 γ+cot^2 δ}$