If the action is asked for, like what action administrator need to do? then correct answer will be C. The field needs to be restored from the recycle bin.
here in question it is asked that What should an administrator take into consideration when undeleting the field?
correct answer will be A. The field needs to be re-added to reports.

Answer b - is not at all correct. As you undelete field , field , data, and field history all will get restore.
Only all other relationship with field, or requirement condition on page layout will be lost.

Correct answer is C. Check this link https://help.salesforce.com/s/articleView?id=sf.fields_managing_deleted_fields.htm&type=5
You can restore your history data from your deleted custom field

correct answer is C, not b