The correct answer is: A. Grade
The penetration test is a standard test used to determine the consistency of bitumen. It measures the depth to which a standard needle penetrates a sample of bitumen under a given load and time. The penetration test is used to classify bitumen into different grades. The higher the penetration, the softer the bitumen.
The viscosity of bitumen is a measure of its resistance to flow. It is determined by the time it takes for a given volume of bitumen to flow through a standard orifice. The higher the viscosity, the slower the bitumen flows.
The ductility of bitumen is a measure of its ability to be stretched without breaking. It is determined by the distance a sample of bitumen can be stretched before it breaks. The higher the ductility, the more ductile the bitumen.
The temperature susceptibility of bitumen is a measure of how its properties change with temperature. Bitumen becomes softer as the temperature increases and harder as the temperature decreases.