Which equation represents a linear function

A.

Step-by-step explanation:

The equation that is a linear function  can be written in the form

For the first option, we have;

Expand;

y=-5x+12

This is a linear function.

For the second option, we have;

Expand;

x+4x=-32-7

5x=-39

This is a constant function.

for the 3rd option, we have;

Expand;

This is not linear because of the xy term

The last option is

this is quadratic.