Answer:
The answer is C. After school today, I’ll go to soccer practice, and then Jamie is supposed to pick me up in her new car.
Step-by-step explanation:
Parallel structure refers to the using of the same pattern of words to show that two or more ideas have the same level of importance. In this case, you can see in letter C that, the future "will" in "I´ll" is being used, however in the second part, which is after the comma, the future is not being used anymore, but the phrase "supposed to" which implies a lack of parallel elements, refering as if Jamie picking her/him up is less important. The other two option have parallelism, same grammar, same pattern of words.