Citizen science data can best address the question: A. How does caterpillar abundance and distribution change over the year?
This question is suitable for citizen science because it involves observational data that participants can collect over time, documenting caterpillar sightings and their locations. Such data can help scientists analyze trends in abundance and distribution related to seasonal changes, which is relevant to understanding ecological dynamics and potential effects of climate change.
The other questions, while interesting, may not be as directly suited to citizen science as they could require more specific knowledge or controlled conditions for accurate data collection (e.g., identifying tree species or specific food preferences).