15
Q:

Some mountains are hillocks. Some mountains are rivers. Some mountains are valleys.

Conclusions:

1. All mountains are either hillocks or rivers or valleys

2. No valley is river

3. Some river are valleys

A) None follows B) Only 1 follows
C) Only 2 and 3 follow D) Only 3 follows

Answer:   C) Only 2 and 3 follow



Explanation:

2 and 3 are the satements involving the extreme terms of the last 2 premises and form a complementary pair. Thus either 2 or 3 follows