Im guessing its B, Because it just makes more sense! I went in there and read it aloud using both words (A and B) B made more sense. With an object being measured, such as a lemon, to make a quart of lemon juice, Id say you'd use the word number. Amount is not a word used for an object or measurement.
Research can be used to prove something true is tell factual info about something! Research is conducted in a wide variety of topics from illnesses to animals etc.
By finding a common interest that both of those people would have whether it is music, Political views, culture or religion etc;
The best answer among the following choices would be the second option B) because C) and D) are normal sentences while B) is complex and A) is fine but needs to replace ''has a tendency'' with ''tends''.