This question calls for Charles' Law (one of the gas laws) because it deals with volume and temperature of a gas. Charles' Law is as follows:
V₁/T₁ = V₂/T₂
Just plug in what you know! The initial volume and temperature (V₁ and T₁) are 2.3L and 24⁰C. The final volume (V₂) is 3.0L. Solve for T₂ algebraically:
2.3/24 = 3.0/T₂ *cross multiply here
2.3T₂ = 72
T₂ = 31.3⁰C
Now, convert to Kelvin by adding 273 to the temperature.
31.3 + 273 = 304.3K
The answer must be D because that is the only option where the balloon would reach at least 3.0L.