Consider the relations r1 (A, B, C), r2 (C, D, E), and r3 (E, F) of Exercise. Assume that there are no primary keys, except the entire schema. Let V (C, r1) be 900, V (C, r2) be 1100, V (E, r2) be 50, and V (E, r3) be 100. Assume that r1 has 1000 tuples, r2 has 1500 tuples, and r3 has 750 tuples. Estimate the size of r1 Θ r2 Θ r3, and give an efficient strategy for computing the join.