For What Nonzero Values Of $k$ Does the Function $y = A \sin k t + B \cos k t$

Multiple Choice

For what nonzero values of $k$ does the function $y = A \sin k t + B \cos k t$ satisfy the differential equation $y ^ { \prime \prime } + 100 y = 0$ for all values of $A$ and $B$ ?

A) $k = 10$
B) $k = - 100$
C) $k = - 10$
D) $k = 100$
E) $k = 1$