At What Values of T Does the Curve X = $\pi$

Multiple Choice

At what values of t does the curve x = t - sin t, y = 1 - cos t have (a) a horizontal tangent, (b) a vertical tangent, and (c) no tangent?

A) (a) t = 2k $\pi$ , k is an integer; (b) t = (2k + 1) $\pi$ ; (c) nowhere
B) (a) t = k $\pi$ , k is an integer; (b) nowhere; (c) nowhere
C) (a) t = (2k + 1) $\pi$ , k is an integer; (b) t = 2k $\pi$ , k is an integer; (c) nowhere
D) (a) t = (2k + 1) $\pi$ , k is an integer; (b) nowhere; (c) t = 2k $\pi$ , k is an integer
E) (a) t = k $\pi$ , k is an integer; (b) t = 2k $\pi$ , k is an integer; (c) nowhere