Which is a change or signal in the environment that can make an organism react? *
stimulus
O reaction
impulse
O
response

I'm pretty sure its stimulus

the answer is definitely c.

the major pests we deal with are insects, weeds and fungal diseases. a pesticide is a product, whether organic or chemical, used to kill the target pest. there are other techniques gardeners should use that can prevent the severe infestations that make the use of pesticides necessary