The most appropriate piece of evidence to support the author's claim that no one should attempt to do yard work when it is cold outside is:
B. Yard work in cold weather is difficult because the ground is too hard and frozen.
This option provides a factual basis for why yard work is not advisable in cold weather, aligning with the author's assertion that working outside in the cold is undesirable. It offers a concrete reason related to the conditions of the ground that directly supports the claim about the impracticality of yard work in such weather.