The neck is a
a. first class lever
b. second class lever
c. third class lever
d. fourth class lever

Answer;

-First class lever

The neck is a first class lever.

Explanation;

-A lever is a simple machine that uses an applied force to rotate a rigid rod about a fixed pivot point/fulcrum with the purpose of lifting a weighted load. There are three major classes of levers, each defined by the location of the applied force or effort in relation to the load or resistance and the fulcrum.

-A first-class lever has its fulcrum placed between the applied force and the load. An example of a first class-lever is a seesaw.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).