Toss a pair of dice two times

Consider tossing a pair of fair dice two times. For each of the following pairs of events, tell whether they are disjoint, independent, or neither.

(a) A = 7 on the ?rst roll, B = 6 or less on the ?rst roll.

(b) A = 7 on the ?rst roll, B = 6 or less on the second roll.

(c) A = 6 or less on the second roll, B = 5 or less on the ?rst roll.

(d) A = 6 or less on the second roll, B = 5 or less on the second roll.