let's see this one by one...
A> is not the answer cause let's say y = 14.
then for first expression it is (3*(14-8))/9 = 18/9 = 2 (integer division)
then for second expression it is ((14-8)/9)*3 = (6/9)*3 = 0*3 (integer division 6/9 is zero.) = 0
B> is not the answer cause let's say y = 15.
then for first expression it is (3*(15-8))/9 = 21/9 = 2 (integer division)
then for second expression it is ((15-8)/9)*3 = (7/9)*2 = 0*3 (integer division 7/9 is zero.) = 0
C> is the answer cause let's say (y-8) = 9K (K belongs to integer).
then for first expression it is (3*9K)/9 = 27K/9 = 3K(integer division)
then for second expression it is ((9K)/9)*3 = K*3 = 3K
D> is not the answer cause let's say (y-8) = 3K (K belongs to integer).
then for first expression it is (3*3K)/9 = 9K/9 = K(integer division)
then for second expression it is ((3K)/9)*3 = (K/3)*3 not equal to K for say (k=5 in integer division)
