Assertion (A): In rhombus ABCD, angle ABC = 120° and length of its each side is 20 cm. The length of diagonal BD = 20 cm. Reason (R): In ΔAOB, cos 60° = and BD = 2 x OB 1. A is true, but R is false. 2. A is false, but R is true. 3. Both A and R are true, and R is the correct reason for A. 4. Both A and R are true, and R is the incorrect reason for A.