Option B:
Both n and m must be rational.
Solution:
Given information:
Sum of two numbers, n and m are rational.
To find which statements are true:
Option A: Both n and m may be rational but do not have to be.
It is not true because n and m given is rational.
It have to be rational.
Option B: Both n and m must be rational.
Yes, n and m must be rational then only the sum of numbers are rational.
It is true.
Option C: Both n and m must be irrational.
Sum of irrationals will be sometimes irrational and sometimes can't add.
So it is not true.
Option D: One number is rational and the other is irrational.
Rational and irrational cannot be add.
So it is not true.
Option B is true.
Both n and m must be rational.