The effectiveness of wind break is up to how many times its height?

Answer: Option C

The effectiveness of wind break is up to 4 times its height.
Important factors related to the efficiency of windbreaks are height, length, vegetation density, number of rows, continuity, orientation and species composition.
On the windward side of a windbreak, wind speed reductions are measurable upwind for a distance of 2 to 4 times the height of the windbreak.