Why does a helicopter have a tail rotor? 1. the tail rotor is just for decoration. 2. none of these 3. this increases safety if any of the rotors breaks down. 4. this keeps the helicopter from spinning out of control?

Abiology teacher asks students to give examples of genetic variations that support the idea that changes in a population’s environment affect genetic variation. which is the least supportive example? a.changes in genetics in human populationsb.antibiotic resistance in bacteria populationsc.pesticide resistance in garden insectsd.changes in the color of the peppered moth population in england