1.) Bob has an old injury in his knee. Every time it rains, Bob's knee starts to hurt. One day, while sitting inside, Bob starts complaining that his knee hurts.
Obviously, that means it must be raining outside.

not necessarily. this is probably a psychological reaction to the rain.

Explanation:

Bob's knee hurts because Bob's wife hit him on the knee, because Bob complains about his knee instead of doing household chores.

credit should be the answer

i would think its c but i'm not sure