invented the microscope wrote a book about the planets created a model of the solar system made improvements to the telescope
I gave my students this multiple choice question: In the 1600s, Galileo Galilei studied the moons of Jupiter. What did Galileo do to make better observations?

Only one answer is correct among these 4 choices:
- invented the microscope
- wrote a book about the planets
- created a model of the solar system
- made improvements to the telescope

Could you tell me which one is correct?

made improvements to the telescope