13. which of the following represents replacement reproduction?
a. each couple has only two children
b. a couple has no children but each has two siblings
c. a government policy that limits the number of children per family
d. a couple with four children
o

The answer is A. Each couple has only two children

Explanation:

The replacement reproductionis inferred to the minimum reproduction that a closed population needs so that it remains endlessly in time without decreasing its volume. This value is around 2.1 children on average. This is understood that a woman must reproduce herself and her partner, the decimal is because there are women who have no children.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.