Which of these is a compound sentence?

The answer is C because that  is the only case of two independent clauses joined by ", and".

do you know the answer?

. a function is a relation in which each input has only one output. in the relation , y is a function of x, because for each input x (1, 2, 3, or 0), there is only one output y. x is not a function of y, because the input y = 3 has multiple outputs: x = 1 and x = 2.