Suppose:

table A has columns X and Y.

table B has columns Y and Z

What is true of the query: SELECT A.X, B.Z FROM A, B?

a. The result is empty if there is no overlap in the values of column Y of table A and column Y of table B

b. The size of the result is the smaller of the sizes (number of rows) of the tables

c. There are 4 columns in the result

d. The size of the result is the product of the sizes (number of rows) of the tables