1 – Correct
Even skiing involves travel. Since all travel damages the environment, it does not prove that ski holiday, which also involves travel does not damage the environment.
2 – Correct
The argument made in the text is that ski resorts use less energy as compared to other resorts. If the information given in sentence 2 is correct, then this conflicts the information given in the text.
3 – Correct
The author fails to consider the damage that is caused by ski industries by factors other than energy consumption.
Since all statements find a weakness in the text, G is the answer.