The right amount of moisture (or maximum water content) for soil to reach the greatest density is called the _____.

The term that describes the right amount of moisture, or maximum water content, for soil to achieve its greatest density is known as optimum moisture content. This is a crucial concept in soil compaction since the density of soil is significantly affected by its moisture content during the compaction process.

Optimum moisture content is determined through testing methods such as the Proctor test, where different moisture contents are evaluated to find the level at which the soil can be compacted to its maximum density.

When soil is at its optimum moisture content, it has enough water to lubricate the soil particles, allowing them to move closer together during compaction. However, if the moisture content is too low or too high, the soil will not reach its maximum density, resulting in inadequate soil strength and stability.

The other options, while related to moisture and soil compaction, do not specifically refer to the ideal water content needed for maximum density.