Which of the Following Template Function Definitions and Invocations Will

Which of the following template function definitions and invocations will not compile,if any? If not,why not?
Assume that classes have been declared with appropriate default constructors and assume that
//a.
template<class A>
A func( A x,A y){ return A();}
int main()
{
U u1,u2,u3;
u2 = func(u2,u3);
}
//b.
template<class B>
B func(){ return 1;}
int main()
{
T t;
t = func();
}
//c.
template<class C>
void func(C x,int * y){}
int main()
{
T t;
int i;
func( t,&i );
}
//d.
template<class D,class E>
void func(D x,E y){}
int main()
{
T t;
U u;
func ( t,u );
}