Answer:
Last option: 7
Explanation:
The Standard form of a quadratic equation is the following:

Where "a" is the quadratic coefficient (This coefficient cannot be 0), "b" is the linear coefficient, "c" is the constant and "x" is the variable.
In this case you have the quadratic equation
which is written is Standarf form. Then, you can identify that:

Therefore the value of "c" is 7.