What question would a biologist most likely investigate?

Which reactions produce decaffeinated coffee?

Do drier growing conditions affect the size of coffee beans?

Why do some people like tea better than coffee?

What is the best temperature for roasting coffee beans?

The question which would a biologist most likely investigate is definitely : Do drier growing conditions affect the size of coffee beans? Because the first thing they should check to expand general knowledge of particular fenomenon is to research its reaction on the environment.