Please help me with this question

(Figure: Predicting Market Shifts) Why is there a tendency for this market to adjust from a price ofP₁toP₂?

a.The government wants to regulate the market.

b.The presence of excess inventories forces firms to cut prices.

c.Insufficient production causes some consumers to offer to pay more for the product.

d.The presence of an economic shortage induces firms to offer lower prices.