Karen is selling ice cream sundaes to raise money for her school orchestra. She wants to purchase the least expensive ice cream, chocolate sauce, and sprinkles so she can earn maximum profits from her sundae sales. The ingredients are all sold at different prices in different-sized packaging so Karen is confused about which ingredients are more expensive and which are less expensive. Help her find the least expensive ingredients based on unit price.
Karen must choose between these three brands of chocolate sauce:

Brand X Chocolate Sauce

A 700-mL bottle costs $10.50.
Brand Y Chocolate Sauce

A 1-liter bottle costs $12.50.
Brand Z Chocolate Sauce

A 100-mL bottle costs $2.00.

Based on the unit price, which of the three chocolate sauce brands should Karen buy?
Show your work and justify your response.