Answer:
A. It is of the finest quality.
Explanation:
The main meaning of the adjective premier is best, leading, most important.
It can also mean first, preceding all others in time.
The given sentence describes Lake Powell, the largest man-made lake in North America. Today it is one of the most popular summer destinations in the US. The adjective premier, in this case, refers to exactly that - it being one of the best, leading water-based recreation destinations in the world.
