You want an equation that includes both V and T. Charles' Law states that V =kT or V₁/T₁ = V₂/T₂, so this is the best formula to use.
B: The Combined Gas Law is p₁V₁/T₂ = p₂V₂/T₂ will work, but it's overkill for the situation. You can assume any constant value for the pressure, and it will cancel from each side of the equation,
C is wrong. Boyle's Law is p₁V₁ = p₂V₂. It does not include the temperature.
D is wrong. Gay-Lussac's Law is p₁/T₂ = p₂/T₂. It does not include the volume.
