Final answer:
The common symptoms of a computer virus include slow performance, frequent crashes, unexplained file changes, unsolicited program activity, frequent pop-ups, and homepage changes.
Step-by-step explanation:
Common Symptoms of a Computer Virus
The two common symptoms of a computer virus are B. Slow computer performance and frequent crashes, as well as C. Unexplained file changes and new programs running without your consent.
In addition to these symptoms, users may also experience frequent pop-ups and unexpected changes to their homepage. Therefore, the correct answer to the question of common symptoms of a computer virus is D. All of the above.