The strength of a soil to the strength of the standard soil is defined as:a.CBR %b.Nonec.AASHTOd.K%

The question pertains to a technical concept regarding soil strength, specifically the relationship of soil strength to a standard in geotechnical engineering. The term you are looking for is:

California Bearing Ratio (CBR) which is a measure used to evaluate the strength of subgrade soil and base courses for pavement design.

The correct answer to your question is:

a. CBR %

Explanation:

1. California Bearing Ratio (CBR) is a penetration test for laboratory and field testing of soils, determining the strength of the material to support the load applied to it.
2. It compares the strength of a given soil sample against a standardized material, providing a percentage that indicates the load-bearing capacity.

Understanding CBR is crucial for civil engineers when designing pavements, as it helps in predicting how much traffic load the pavement can sustain without excessive deformation or failure.