Suppose you are passing a vector of ints (named vec) to a function (named delete_half), and you want to have the function delete the last half of the vector. How should you pass the vector to the function? In other words, what should the function signature look like? A function signature means something like this: int main(); O void delete_half(vector &vec); O static vector int> delete_halfo); O void delete_half(const vector vec): void delete_half(vector vec); O vector int>& delete_half(void)