The correct answer is A. Pressure.
When it comes to lake effect snow the two main ingredients when forecasting it is, strong winds that blow over open water, and temperatures well below freezing, or temperatures much colder than the water temperature.
The atmospheric pressure being low may help produce more snow, but it is not necessary for lake effect snow to form. It's common to see lake effect snow during times of rising pressure, or even high pressure.
Here are the results.
A. Pressure - 73% of the vote.
B. Temperature - 9% of the vote.
C. Wind - 12% if the vote.
Thank you to everyone who guessed! I'll have more Weather Trivia tomorrow.