In the Previous Two Problems, the Product Solutions Are
A) $\sin ( n \pi x / L ) \sin ( n \pi / L )$

Multiple Choice

In the previous two problems, the product solutions are

A) $\sin ( n \pi x / L ) \sin ( n \pi / L )$
B) $\sin ( n \pi x / L ) \cos ( n \pi / L )$
C) $\cos ( n \pi x / L ) \cos ( n \pi / L )$
D) $\sin ( n \pi x / L ) e ^ { n x / L }$
E) $\cos ( n \pi x / L ) e ^ { - n t / L }$