Explanation:

Let’s break this down, here’s what each option is saying:

- Option 1 says people can join as plaintiffs if their rights all come from the same act. That’s true, but it’s not the whole story.

- Option 2 says joining is allowed when there’s a common legal question—so if everyone’s cases hinge on the same rule or issue, they can join too.

- Option 3 covers both: same act and/or common question of law. This is actually what you’ll find in the law (Order 1, Rule 1 CPC in India for example). It lets you join as plaintiffs if either you share a common legal question, or your rights arise out of the same act.

- Option 4, none of the above, is definitely out.

So here’s what this really means: Option 3 is the correct answer.