Explanation:

- The statement refers to *Avogadro's Law*.

- It states that equal volumes of gases, at the same temperature and pressure, contain an equal number of particles.

- This law is fundamental in understanding the behavior of gases.

Option 1: Charles

- *Charles's Law* relates volume and temperature. It states that the volume of a gas is directly proportional to its temperature, provided pressure is constant.

Option 2: Boyle

- *Boyle's Law* focuses on pressure and volume. It states that the volume of a gas is inversely proportional to its pressure, assuming temperature is constant.

Option 3: Avogadro

- *Avogadro's Law* talks about volume and number of particles in gases, matching the given statement.

- Correct Answer: Avogadro

Option 4: Lussac

- *Gay-Lussac's Law* involves pressure and temperature. It states that pressure is directly proportional to temperature, assuming volume is constant.