The student can choose any one of 3 sandwiches. For each of those . . .
He can choose any one of 3 soups. For each of those . . .
He can choose any one of 4 salads. For each of those . . .
He can choose either one of 2 drinks.
Total possibilities = (3 x 3 x 4 x 2) = 72 different lunches.