ANS:B - Ball and ring

The test done to find out the softening point of bitumen is the ball and ring test.

Explanation:

1. Ball and Ring Test:
   • The ball and ring test, also known as the "Ring-and-Ball Softening Point Test," is a standard method used to determine the softening point of bitumen and asphalt materials.
   • In this test, a steel ball is placed on a bitumen sample contained in a brass ring, which is then heated in a water or glycerin bath. The temperature at which the bitumen softens enough to allow the ball to fall a specified distance is recorded as the softening point.
2. Other Tests:
   • Impact Test: Typically used to measure the toughness or impact resistance of materials, not applicable for determining the softening point of bitumen.
   • Flame Test: Used to identify the presence of certain elements based on the color of the flame they produce, not relevant for bitumen.
   • Viscosity Test: Measures the flow characteristics of bitumen, not specifically the softening point.

Conclusion: