Mary and Jane are always quarrelling with ______.

Analyze the question The sentence needs a word that shows a reciprocal relationship. Mary quarrels with Jane, and Jane quarrels with Mary.

Explain the concept

• Reciprocal pronouns are "each other" and "one another". They show that two or more people do the same thing to one another.
• Traditionally, "each other" is used for two people or things, and "one another" for more than two.
• Reflexive pronouns such as "themselves" show that the action returns to the doer (e.g., They hurt themselves).

Step-by-step solution

1. There are two people, Mary and Jane, so we need a reciprocal pronoun for two people.
2. A. each other is reciprocal and fits two people. ✔
3. B. themselves would mean each girl quarrels with herself, which is not the intended meaning.
4. C. another is incomplete. It would need "one" before it ("one another"), and it is also better suited to more than two people.
5. D. either means "one or the other of two". It does not fit grammatically here.

The sentence reads: Mary and Jane are always quarrelling with each other.

Answer: A. each other

Exam tip Ask yourself, "Is the action going both ways between two people?" If yes, choose each other. Remember: each other = 2, one another = 3 or more. "Themselves" is for actions that return to the doer.