Answer: a. Excuse himself and check back when the call is complete.
Explanation:
In saying that she must take that call, she is indirectly suggesting that she requires privacy. George should give her the room to answer and check back when she is done because it is not only the courteous thing to do, but the business savvy decision as well.
The other options may likely result in the termination of his business relationship with her due to a perceived lack of patience and/or disrespect so simply excusing himself and coming back after her call is the correct decision all else being equal.
