Find all solutions y(x) of the boundary value problem y′′+y=0, y′(0)=0, y(π)=1. The k below is an arbitrary constant.
A) y(x) does not exist.
B) y(x)=−sin(x)
C) y(x)=sin(x)+kcos(x)
D) y(x)=−cos(x)
E) None of the above