$$y = x ^ { 2 } - 2 ( a + 1 ) x + a ^ { 2 } - 1$$
If the parabola is tangent to the line $y = 1$, what is a?
A) $\frac { -3 } { 2 }$
B) $\frac { -3 } { 4 }$
C) 0
D) 1
E) 2
$$y = x ^ { 2 } - 2 ( a + 1 ) x + a ^ { 2 } - 1$$

If the parabola is tangent to the line $y = 1$, what is a?

A) $\frac { -3 } { 2 }$\\
B) $\frac { -3 } { 4 }$\\
C) 0\\
D) 1\\
E) 2