Help me with this please

Explain why biological control methods are generally environmentally superior to chemical pest control methods.

Astudent poured a solution of bromothymol blue indicator into three test tubes. then he placed an aquatic plant in two of the test tubes, as shown below. he placed a stopper on each test tube and placed them all in the dark for 24 hours. bromothymol blue turns from blue to yellow in the presence of co2

They live on every continent except antarctica