A, you don't have to take any measures, just let it go.
B. You may apply to the Trademark Review and Adjudication Board to declare the registered trademark invalid.
C. An application for invalidation may be filed within 5 years from the date when a registered trademark is approved for registration.
D, you can file an invalid application within 10 years from the date when the registered trademark is approved for registration.
Correct answer: ABC