Final answer:
Option A uses commas correctly to clarify the meaning of the sentence.
Step-by-step explanation:
The sentence that uses commas correctly to clarify the meaning of the sentence is option A. In this sentence, the commas correctly separate the items in the series of high-quality shoes, socks, and running clothes. The commas help to avoid any confusion and make it clear that all three items are needed for training as a long-distance runner.