The statement is given as,
The sum of 16 and 11 is represented as,

Let this sum is represented by letter S,

According to the statement, this sum S is to be subtracted from 43.
This can be written as,

Substitute the value keeping in mind that the parenthesis will be used to denote S as a single term,

Thus, the correct expression for the given statement is,

Therefore, option C is the correct choice.