When a regression model was developed relating sales (Y) of a company to its product's price (X₁), the SSE was determined to be 495. A second regression model relating sales (Y) to product's price (X₁) and competitor's product price (X₂) resulted in an SSE of 396. At a = 0.05, determine if the competitor's product's price contributed significantly to the model. The sample size for both models was 33.

In comparing the two models the correct null hypothesis for testing which model has significantly lower SSE is:

a - H0: B1 = B2 = 0

b - H0: B1 = 0

c - H0: B2 = 0

d - H0: Both (a) and (b)