Need help with this C code. I don't understand how the call by reference is working or how the arguments for double meansqr work. Please complete it for me so that it executes in main and prints the result. Also please add the option for the user to enter in the values of a.

double meansqr(double *a, int size) { double sum = 0.0; int i; for (i = 0; i

return mean;