What chapter is this question about?
It suggests the narrator is lost quite frequently
Option C contains a run-on sentence (I would call it a comma splice).
A better way to phrase the sentence could be:
1. A giant clam grows huge; it can weigh hundreds of pounds.
2. A giant clam grows huge. It can weigh hundreds of pounds.
Answer:
Liesl worries about losing ties to her home culture, while her brother looks forward to joining a new culture.
Explanation: