In the Previous Four Problems, the Infinite Series Solution of the Original

Multiple Choice

In the previous four problems, the infinite series solution of the original problem is (for certain values of the constants $a _ { n }$ and $b _ { n }$ )

A) $u = \sum _ { n = 1 } ^ { \infty } a _ { n } J _ { 0 } \left( z _ { n } r / 2 \right) \cos \left( z _ { n } t / 2 \right)$
B) $u = \sum _ { n = 1 } ^ { \infty } b _ { n } J _ { 0 } \left( z _ { n } r / 2 \right) \sin \left( z _ { n } t / 2 \right)$
C) $u = \sum _ { n = 1 } ^ { \infty } b _ { n } J _ { 0 } ( n \pi r ) \sin ( n \pi t )$
D) $u = \sum _ { n = 1 } ^ { \infty } a _ { n } J _ { 0 } ( n \pi r ) \cos ( n \pi t )$
E) $u = \sum _ { n - 1 } ^ { \infty } J _ { 0 } \left( z _ { n } r / 2 \right) \left( a _ { n } \cos ( n \pi t ) + b _ { n } \sin ( n \pi t ) \right)$