Lately, Christina has been battling vertigo, but she's keeping it a secret from everybody. The dizziness comes upon her all of a sudden, usually when she is descending a particularly steep staircase. She's too proud to go to the doctor, though. She says that she prefers to not be a burden on others. Select the word that offers the best synonym for vertigo.

A. descending

B. burden

C. secret

D. dizziness