4 letters have to be put into their 4 respective envelopes. If the letters are inserted randomly into the envelopes, what is the probability that all the letters go into their respective envelopes?	Select the correct option:
A) 1/30
B) 1/64
C) 1/120
D) 1/240
E) 3/5
A-B-C-D-E (envelopes)   a-b-c-d-e (letters)   4 letters (a, b, c, d, and e) can be assigned to 4 envelopes (arranged) in 4! ways, out of which only one will be correct, thus the probability is 1/4! = 1/64.   Answer: 1/64.
<result>B</result>
4 letters have to be put into their 4 respective envelopes. If the letters are inserted randomly into the envelopes, what is the probability that all the letters go into their respective envelopes?