NIce puzzle the answer is (e)
tis is quite simple if we use elimination method.....
A manager must be on duty each day. - so in (a) there r no managers
The managers cannot work on the same day. - so in (b) there r 2 managers
W and X will not work on the same day. - so (c) is not the answer
At least two tellers must be working on the same day. - so its not (d)
Hence the Answer is (e).....
THANK U FOR SUCH A GREAT PUZZLE......