The correct answer to the question is option B, which states that the first and second numbers in the bitumen grades (e.g., 65/25, 85/40) refer to penetration and softening point, respectively.

Explanation:
The classification of bitumen by the Bureau of Indian Standards (BIS) is based on several properties that determine its suitability for various applications. Two important properties that are commonly used to classify bitumen are penetration and softening point.

1. Penetration: Penetration is a measure of the hardness or consistency of bitumen. It represents the depth, in tenths of a millimeter, to which a standard needle will penetrate the bitumen sample under specific conditions of time, temperature, and loading. A lower penetration value indicates a harder bitumen, while a higher penetration value indicates a softer bitumen.

2. Softening Point: The softening point is the temperature at which bitumen becomes soft enough to flow under the influence of heat or load. It is determined by the ring-and-ball method, where a brass ring containing a bitumen sample is heated and the temperature at which the bitumen touches a brass ball is recorded. A higher softening point indicates a harder bitumen, while a lower softening point indicates a softer bitumen.

Now, let's consider the given bitumen grades: 65/25 and 85/40.

- In the grade 65/25, the first number (65) represents the penetration value. This means that the bitumen has a penetration value of 65 (in tenths of a millimeter) under the specific test conditions.

- The second number (25) in the grade 65/25 represents the softening point. This means that the bitumen has a softening point of 25 degrees Celsius.

Similarly, in the grade 85/40, the first number (85) represents the penetration value, indicating that the bitumen has a penetration value of 85 (in tenths of a millimeter) under the specified test conditions. The second number (40) represents the softening point, indicating that the bitumen has a softening point of 40 degrees Celsius.

Therefore, the correct answer is option B, as the first and second numbers in the bitumen grades refer to penetration and softening point, respectively.