Given the following main program:

int main() { int x; int y = 10; int z = 20; x = add(y,z); return 0; }

Which function is correctly written to store the value in x?

		int add(int a, int b) { return a+b; }
		float add(float a, float b) { float x; x = a + b; return x; }
		void add(int y, int z) { int x; x = y + z; return; }
		int add(y, z) { int x; x = y + z; return x; }