Explanation:

- Sulphur is a chemical element represented by the symbol 'S'.

- It is found in Periodic Table's Group 16, also known as chalcogens.

- The atomic number of an element equals the number of protons in its nucleus.

Let's examine the options provided:

- Option 1: 15

- This atomic number belongs to phosphorus (P), not sulphur.

- Option 2: 14

- This atomic number is for silicon (Si).

- Option 3: 16

- This is indeed the atomic number for sulphur.

- Option 4: 18

- This atomic number is for argon (Ar), one of the noble gases.