Answer:
The phrase that should be included to improve the clarity of the sentence is:
A. meaning they touch the snow only in the middle of the board.
Explanation:
Someone who does not snowboard will probably find the original sentence to be a little difficult to understand. We do not know what a camber is. Thus, for the author of the sentence to improve its clarity, that is, to make the sentence understandable to anyone who reads it, he must explain what a camber is.
Among the options, the only one that does that is the first one. The other options only explain that a camber is a technology used in snowboarding, but we still do not know what it is or what it does. However, the first choice lets us know that an inverted camber means the board only touches the snow in its middle. Therefore, it improves clarity.
