the correct answer is c. the use of consistent patterns that keep the elements in a series in the same form.
parallel structure, also known as parallelism, is the use of the words in a sentence with the same patterns to attain the same importance for each word. it should be used when connecting words, such as for, and, or etc. are present. one example is: paul likes playing soccer and to swim. (not parallel). paul likes playing soccer and swimming. (parallel)