Answer:
Option B is correct. Ivan Pavlov's report his findings as "Pavlov's dog salivated when the meat powder was presented."
Explanation:
In standard English the research findings are written in simple past tense because he observed the said phenomenon in the past.
Hence, option A,B, and D are incorrect.
So we can conclude that Option B is correct. Ivan Pavlov's report his findings as "Pavlov's dog salivated when the meat powder was presented."
For more about English grammar you can refer to the link:
https://brainly.com/question/21871399?referrer=searchResults