The sentence that uses parallel structure is option B) “Daily exercise increases athletes' stamina, endurance, and strength”. Parallel structures are writing resources that help bring coherence to a sentence by using the same grammar pattern when listing items or actions. In this example, parallelism is maintained by using nouns after the word athletes’ such as “stamina, endurance and strength”.
In the rest of the options there is a break in the grammar pattern so no parallel structure is possible. In option C for example, the sentence mixes the nouns “stamina and endurance” with the verb to be+ ing as in “is strengthening”. In option D there is also a break in maintaining the same grammar structures since it mixes noun (stamina), verb+ object (increases their endurance) and verb to be+ ing( is strengthening)
