The correct answer is: B. Expansion in supply.
Expansion in supply is a situation in which the quantity supplied of a good or service increases at any given price. This can be caused by a number of factors, such as a decrease in the cost of production, an increase in the number of producers, or an increase in the demand for the good or service.
A fall in supply is a situation in which the quantity supplied of a good or service decreases at any given price. This can be caused by a number of factors, such as an increase in the cost of production, a decrease in the number of producers, or a decrease in the demand for the good or service.
A contraction in supply is a situation in which the quantity supplied of a good or service decreases at any given price. This is the opposite of expansion in supply.
A rise in supply is a situation in which the quantity supplied of a good or service increases at any given price. This is the opposite of a fall in supply.
In the case of the question, the supply of a commodity increases without change in price. This means that the quantity supplied of the commodity increases at any given price. This is a situation of expansion in supply.