(a) If A is a 4 x 6 matrix, what is the largest possible rank of A? (b) If A is an mxn matrix, what is the largest possible rank of A? O The largest possible rank is always m + n. O The largest possible rank is always n. O The largest possible rank is always m. O The largest possible rank is the larger of the two numbers m and n. The largest possible rank is the smaller of the two numbers m and n.