ANS:A - scratch

Mho's scale of hardness, also known as the Mohs scale of hardness, is used for the measurement of scratch hardness. The Mohs scale of hardness is a qualitative scale that ranks the hardness of minerals based on their ability to scratch each other. It consists of 10 standard minerals, with each mineral being assigned a hardness value from 1 (the softest) to 10 (the hardest). For example, talc has a hardness of 1, while diamond has a hardness of 10. To determine the hardness of a mineral using the Mohs scale, one mineral is scratched against another. If the mineral being tested is scratched by another mineral, it has a lower hardness value. If it scratches the other mineral, it has a higher hardness value. So, the Mohs scale of hardness is primarily used for measuring scratch hardness.