10. Let line $l$ intersect the parabola $y ^ { 2 } = 4 x$ at points $\mathrm { A }$ and $\mathrm { B }$, and be tangent to the circle $( x - 5 ) ^ { 2 } + y ^ { 2 } = r ^ { 2 }$ $(r > 0)$ at point $M$, where $M$ is the midpoint of segment $A B$. If there are exactly $4$ such lines $l$, then the range of $r$ is\\
(A) $( 1, 3 )$\\
(B) $( 1, 4 )$\\
(C) $( 2, 3 )$\\
(D) $( 2, 4 )$
II. Fill in the Blanks\\