The correct answers are as follows:
1. Alex and Martha say goodbye to EACH OTHER after school.
2. The puppies playfully bit ONE ANOTHER on the nose.
3. The mom and dad loved EACH OTHER very much.
4. The children fought with ONE ANOTHER on the play ground.
Reciprocal pronouns are pronouns which are used to indicate that two or more person are carrying out a particular action. There are only two types of reciprocal pronoun, these are 'each other and one another'.
Each other is used when two people are been referred to and one another is used when more than two persons are been refereed to.
In the question given above, you will notice that for question 1 and 3 two people are been refereed to, that is why each other is used, while for question 2 and 4 more than two people are been referred to, that is why one another is used.
