Which Sentence Lacks Parallelism

Multiple Choice

Which sentence lacks parallelism?

A) The seminars will be held on February 14, March 15, and April 1.
B) Victoria is proficient not only in word processing but also in database management.
C) Our word processing program includes pull-down menus, scroll bars, and sentences can be checked for grammatical errors.
D) Students will learn how to write effective messages, make persuasive speeches, and handle themselves in interviews.
E) The new smoke detector is both efficient and effective.