Which type of selection leads to increased phenotypic and genetic variation?

Its disruptive selection.

Explanation:

Nature selects those variations which can be inherited and makes the survival  better so that the individual carrying these useful variations reproduce and form more number of progeny. This effect of natural selection can be stabilizing, directional and disruptive.

Disruptive selection: It is a type of natural selection where mean character value is not preferred but both the peripheral character values are preferred by the nature. For example in a population, if nature selects both the tall and dwarf people but not the medium height people then it is called disruptive selection.

In case of directional selection only one of the extreme character value is selected by the nature. For example in a population, if nature selects only the tall people or only the dwarf people then is is said to be directional.

Stabilizing selection is when nature favors the mean character value i.e. if nature favors or selects the medium sized individuals, then the selection is said to be stabilizing. We get a bell shaped graph for stabilizing selection.

you know they are heterozygous for a trait because they have it as jj or jj.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.