I would go with A. Money.
Hope that helps you. =)
Wiping off the surface of the lab table with a disinfectant
I think that the best phrase to fit into the blank is a "scientific theory".
A scientific theory is developed through experiments which use the scientific method, and a theory can be improved if additional data is available or if people provide suggestions which make the theory fit the data better.
Answer:
The synchronous orbit appears to make the moon more vulnerable to meteor strikes
