Final answer:
To join four tables, we need three search conditions with equality between two columns in the WHERE clause.
Step-by-step explanation:
In order to join four tables, we need to have three search conditions (arguments) with equality between two columns in the WHERE clause. This can be achieved by joining each table with the next table using a common column.
For example, if we have tables A, B, C, and D, we can join them using the following search conditions:
- A join B on A.column1=B.column2
- B join C on B.column3=C.column4
- C join D on C.column5=D.column6
Therefore, the answer is B. 3.