You, or anyone else, can look it up if you like. Here is the official rule (cut and paste). If you find an alternate source to back up the current rule let us know.

(from http://www.cybercom.net/~damish/backgammon/bg-rules.html AND my game rules and any book I have ever read)

"A player is compelled to take his complete move if there is any way for him to do so. If he can take either of the numbers but not both, he must take the higher number if possible, the lower if not."