Your Answer is

Correct Answer is E

Explanation

The title wants to ask if both cross-country and downhill have been slid. According to 1, a total of 65 people have slid either of them. According to 2, we know that 37 people have not slid downhill, that is to say, 37 people only slid cross-country, according to 3, we know that 20 people have not skated cross-country, that is to say, 20 people only skated downhill, so all skated is 65 people, excluding 20 people and 37 people, that is 8 people, so choose E