Ans. (d). temporal lobe.
Temporal lobe is the region of the brain, which is associated with vision, and interpretation of language and sounds we hear. Damage to temporal lobe due to injury or infection can leads to problems with language skills, vision, and memory.
As in infant, scarlet fever ended up with blindness, problems with hearing and speaking, the brain area affected by the scarlet fever is 'temporal lobe.'
Thus, the correct answer is option (d).