Just five years ago, Quebec was _____________ in protecting its natural heritage, but now they have caught up.

The phrase ‘behind the curve’ means ‘less advanced, or developing, understanding something, or reaching a point more slowly than other things or people’. It is correct here. Ahead of the curve- more advanced, or developing, understanding something, or reaching a point more quickly than other things or people. It is inappropriate here. Frontloading- to put or have more payments, charges, activities, etc. close to the beginning of a period. It is contextually incorrect. Elevated- to raise something or lift something up.