Which rational numbers are equal to their reciprocals?

1. 0, 1

2. -1, 0

3. -1, 1

4. -1, 0

A number is equal to its own reciprocal only when its product with itself is 1.

⇒ 1 × 1 = 1

⇒ (-1) × (-1) = 1

Also, 0 has no reciprocal at all.

Hence, Option 3 is the correct option.