Answer:
Barbara investigating that which food the ants like the most in order to use this food for killing the ants and removes them from a specific area.
Explanation: Ants are insects which sometimes act as pest because it lives in holes in the house and act as a carrier of many harmful diseases so in order to control the spreading of the disease we have to control the population of ants.
Genetic engineering is the direct manipulation of a specific gene. I would use it in this scenario
External stimulus. The rain is something out of your control while you're waiting. Rain is not something you are doing nor is it a response to you waiting for the bus.
