含有杂原子的不饱和基团的跃迁类型是()。A. pi arrow pi^*B. n arrow sigma^*C. sigma arrow sigma^*D. n arrow pi^*

A. $\pi \rightarrow \pi^*$

B. $n \rightarrow \sigma^*$

C. $\sigma \rightarrow \sigma^*$

D. $n \rightarrow \pi^*$