Question

A, B and C are integers. A minus B is even and A minus C is odd. which of the following must be odd? 

Answer 1

Answer:

C: B+C

Step-by-step explanation:

A-B is even so A and B are either both even or odd.

A-C is odd so one is even and the other is odd.

Because A is common to both cases B and C have to be of different parities.

In answer A, B, and D we are not sure of the parity of the numbers.

However, in answer C we know that B and C are of different parities, and and even plus and odd is odd.