Final answer:
Marta agreeing to list a commercial property even though her expertise is in residential real estate.
Step-by-step explanation:
Out of the options given, Marta agreeing to list a commercial property even though her expertise is in residential real estate is an example of an agent not executing the duty of reasonable skill and care. This is because Marta should have referred the commercial property to an agent with expertise in that area to ensure that the client receives the best possible service. By taking on a task outside her area of expertise, Marta is not acting in the best interest of her client and may not be able to provide the necessary knowledge and guidance for the transaction.