All ripe mangos are sweet. Some mangos are sour. Therefore:
AAll mangos ripen.
BNo mango is sweet.
CSour mangos are unripe.
DMangos are fruits.
Answer & Solution
Correct answer: C. Sour mangos are unripe.
1. Sour ⊂ not-sweet ⊂ not-ripe. (Contrapositive).
_Source: 501-GMAT-Questions Ch 2 Critical Reasoning_