Assume that the following two tables are given:

T1(A, B, C, D) and T2(B, D, E, F)

Write FROM clause to join the tables T1 and T2, do not use WHERE clause.

1. join T1 and T2 unconditionally
2. join T1 and T2 only when the corresponding B-values and D-values are the same
3. join T1 and T2 only when the corresponding B-values are the same
4. join T1 and T2 only when the corresponding A-value is greater the F-value and the D-values are the same