[填空题]
For each of the following atomic transitr* 2oel g)e(ndions, str/4xc .tcx-s sate whether the transition is allowed or forbidden, and if forbicx.ss- t /cr4xdden, what rule is being violated:
(a) $3p \to 4p$
(b) $1s \to 2p$
(c) $3d \to 2d$;
(d) $4d \to 2p$;
(e) $4s \to 2p$.
