16. Using each of the ten digits $0 \sim 9$ exactly once to form two five-digit numbers. If the sum of the two numbers is to be maximized, then one of the numbers is ( ).
(A) 76531
(B) 86724
(C) 87431
(D) 96240
(E) 97403
16. C.

Obviously, the numbers in options B, D, and E are not arranged in descending order, so their sums are not the largest. Therefore, we only need to discuss options A and C. By forming the largest five-digit number with the remaining digits and adding it to the given number, we can verify that the sum with option C is the largest.