Let Q be the point where the tangent line at point $\mathrm { P } ( a , b )$ on the parabola $y ^ { 2 } = 4 x$ meets the $x$-axis. When $\overline { \mathrm { PQ } } = 4 \sqrt { 5 }$, what is the value of $a ^ { 2 } + b ^ { 2 }$? [3 points]\\
(1) 21\\
(2) 32\\
(3) 45\\
(4) 60\\
(5) 77