Question

appropriate cross country ski length is dependent upon the patrons... skiing ability height center of gravity wing - span weight

Explanation:

When determining appropriate cross - country ski length, a patron's height is a key factor. Skiing ability is more about skill level and not a direct physical measurement for ski length. Center of gravity affects balance during skiing but not the length of the ski. Wing - span is not a relevant measurement for cross - country ski length. Weight can impact aspects like flotation in some skiing (like in powder for alpine skiing), but for cross - country skiing length, height is the primary physical measurement used to determine the appropriate ski length.

Answer:

Height