Data sufficiency (siblings and lineage): How is B related to C? Given: D is the brother of B. Which statements are necessary? (1) The son of D is the grandson of C. (2) B is the sister of D. Choose the correct necessity condition.
Verbal Reasoning
Blood Relation Test
Difficulty: Easy
Choose an option
Answer
Correct Answer: 1 and 2 both are required
Explanation
Use (1)D's son is C's grandson ⇒ D is a child of C.
Combine with (2)B is the sister of D, so B is also a child of C ⇒ B is C's daughter.
Necessity
- (1) alone: identifies D as C's child, but B's gender is unknown ⇒ cannot say “daughter”.
- (2) alone: does not connect B/D to C at all.
ConclusionBoth (1) and (2) are required.