Let $a$ be a real number. The number of distinct solutions $( x , y )$ of the system of equations $( x - a ) ^ { 2 } + y ^ { 2 } = 1$ and $x ^ { 2 } = y ^ { 2 }$, can only be\\
(a) $0,1,2,3,4$ or 5\\
(b) 0, 1 or 3\\
(c) 0, 1, 2 or 4\\
(d) $0,2,3$, or 4