Final answer:
When Rosemary buys a $500 printer on account, the impact on the Accounting Equation is: assets increase and liabilities increase.
Step-by-step explanation:
When Rosemary buys a $500 printer on account from Dwight at Dunder-Mifflin, the impact on the Accounting Equation is: a) Assets increase; Liabilities increase
Buying the printer increases the assets of Rosemary's business because she now has a printer worth $500. At the same time, the purchase creates a liability because Rosemary owes Dwight $500 for the printer.