2's complement and 2's complement representation are different.
In 2's complement representation, positive no is represented as they are and neg no is represented in 2's complement form.
28 in binary = 11100, expanded to 16 bits = 0000 0000 0001 1100
1's complement of this binary no = 1111 1111 1110 0011
Add 1 to get 2's complement = 1111 1111 1110 0100
Ans should be option C.
https://www.cs.cornell.edu/~tomf/notes/cps104/twoscomp.html