Q: You are presented with the quiz "What causes stars to produce light?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "nuclear reactions in stars causes stars to produce light" and "like the Sun, stars generate light and heat through nuclear fusion". So, what's the best answer to the question? | OPTIONS:
- nucleus
- energy
- gases
- mitosis
- fusion
- chemicals
- fire
- boiling
A: fusion

Q: You are presented with the quiz "What causes cancer?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "smoking causes direct damage to the lungs" and "smoking causes lung cancer". So, what's the best answer to the question? | OPTIONS:
- wind
- Roundworms
- abstinence
- steroids
- smoking
- lungs
- influenza
- viruses
A: smoking

Q: You are presented with the quiz "What has a nervous system?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "most invertebrates have a nervous system" and "insects are the most common invertebrates". So, what's the best answer to the question? | OPTIONS:
- animals
- tortoises
- crocodiles
- sponges
- elephants
- placozoans
- mesozoans
- insects
A: insects

Q: You are presented with the quiz "Viruses are so small that they can be seen by what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "viruses are so small that they can be seen only with an electron microscope" and "once the camera is tuned with the microscope, the focusing depends on the microscope lens". So, what's the best answer to the question? | OPTIONS:
- focusing a lens
- A computer
- looking close
- rays or beams
- sunlight
- bending light rays
- seeing smaller
- tuning eyes
A: focusing a lens