Question

drag the missing word into place
the rate that an object falls? well, we can prove it (\how?\),
by forming a(n) ,
an educated guess, or what our thought process is.
hypothesis
method
observation

Explanation:

The sentence describes an "educated guess" which is the definition of a hypothesis. "Method" refers to a procedure, and "observation" is about noticing, neither of which match the description of an educated guess.

Answer:

hypothesis