Suppose A is the augmented matrix of a linear system of 4 equations in 4 variables.(a) What are the dimensions of A? A is __X___(b) If the system has no solutions, what are the possible values for rank(A)? rank(A) = ____(c) If the system has exactly one solution, what are the possible values for rank(A)? rank(A) = ____(d) If the system has infinitely many solutions, what are the possible values for rank(A)? rank(A) = ____.