In this task, you are given a question. You have to answer the question based on your information.

Let me give you an example: Roman Yakub won first price in a Choral Composition Competition at a liberal arts college founded by who?
The answer to this example can be: William Egbert
Here is why: This is a good example, and output correctly answers the question.

OK. solve this:
What optical device is the Dutch scientist, after whom the lunar crater Jansen is named, credited for?
Answer:
optical telescope