Answer:
Despite his nerves, he was ready for his first interview; he had thought through each potential question.
Step-by-step explanation:
It is best to put a semicolon before the part “he had thought through each potential question”. This part can stand as a separate sentence, which is why it is correct to put semicolons here, and not after “Despite his nerves” like in example B. This part is dependent on the rest of the sentence.
The reason why it can also be put after the semicolon is the fact it adds the information to what has been said before. Because Sameer thought through the questions, he is feeling ready. This is why example A is not correct – it includes the word although, which would mean that he was ready despite doing something and not because of it.
Example C is not correct because it provides no connection between the first and second parts of the sentence.