15. If the tangent at the point $P$ on the circle $x ^ { 2 } + y ^ { 2 } + 6 x + 6 y = 2$ meets the straight line $5 x + 2 y = 6$ at a point $Q$ on the $y$-axis, then the length of $P Q$ is\\
(A) 4\\
(B) $2 \sqrt { } 5$\\
(C) 5\\
(D) $3 \sqrt { 5 }$\\