4. If the sum of two prime numbers is 85, then the product of these two prime numbers is ( ).
(A) 85
(B) 91
(C) 115
(D) 133
(E) 166
4. E.

These two prime numbers cannot both be odd primes, so one of them must be the even prime 2, making the other prime 83.
Therefore, $83 \times 2=166$.