The correct option is B A member of an older group of beginners.
The first line of the passage mentions that the author began learning skiing on the second stay of his trip. So, this eliminates option A) a trainer of young children learning to ski, as the author is still himself learning how to ski. Option B cannot be the answer because had he been going to the institute often, he would not have been 'clumsier than toddlers' as a skier. The passage does not mention that the author's children were the toddlers, so option D cannot be the correct answer either. The answer is option C) a member of an older group of beginners.