下列计算最大公约数的递归过程，正确的是___________。

A、Sub gcd(ByVal m%, ByVal n%) Dim r% r = m / n If r = 0 Then gcd = n Else gcd = gcd(n, r) End If End Sub
B、Sub gcd(ByVal m%, ByVal n%) Dim r% r = m Mod n If r = 0 Then gcd = n Else gcd = gcd(n, r) End If End Sub
C、Function gcd%(ByVal m%, ByVal n%) Dim r% r = m / n If r = 0 Then gcd = n Else gcd = gcd(n, r) End If End Function
D、Function gcd%(ByVal m%, ByVal n%) Dim r% r = m Mod n If r = 0 Then gcd = n Else gcd = gcd(n, r) End If End Function