Roger Corp is organized in Canada. It enters into a contract with Danielle, a United States citizen, under which Danielle serves as Roger's exclusive agent in selling Roger's products in the United States. Danielle receives a commission for each sale to a United States customer. The contract prohibits Danielle from selling any competing products in the United States and from acting as the agent for another in selling any competing products in the United States.

a. Is Roger Corp's income subject to tax in the United States?

b. How would your answer to (a) change if Danielle also serves as a commission agent for Roger Corp's competitors' products, but habitually exercises her authority to conclude contracts for Roger Corp?