$l, \; m, n$ are the $p^{th}, q^{th}$ and $r^{th}$ term of an GP and all positive, then $\begin{vmatrix} \log l & p & 1 \\ \log m & q&1 \\ \log n & r & 1 \end{vmatrix}$ equals :

Question

( A ) 1
( B ) 2
( C ) zero
( D ) 3