The correct term to indicate the inability to speak following a stroke is Option B: aphasia. Aphasia refers to a disorder that affects communication, which can include speaking, understanding speech, reading, and writing.
Option C: dysphasia is sometimes used interchangeably with aphasia, but it often refers to a less severe impairment, so it is not the best choice in this context where the ability to speak is lost following a stroke.
Option A: anoxia refers to a lack of oxygen, which is not directly related to the inability to speak.
Option D: dyslexia is a learning disorder characterized by difficulty reading, which is also not applicable in this case.
Therefore, the best choice is B: aphasia.