GMAT Critical Reasoning (CR) | Re: The U.S. Department of Agriculture divides the North America

Hardiness zones are divided based on two parameters - average winter temperature (13 zones) and length of growing season (11 zones).

The last sentence says "Minneapolis is in hardiness zone 4 and Denver is in hardiness zone 6". Do we know based on which parameter this statement is made? Average winter temperature or length of growing season? We don't know.

D: Zones based on two parameters closely correlate, but don't exactly match. So definitely there is some other factor which causes
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