Final answer:
Two-factor authentication, alerts and notifications, and fraud protection services are controls implemented by financial institutions to protect bank accounts when debit cards are used for online transactions.
Step-by-step explanation:
One control that financial institutions have implemented to protect bank accounts when debit cards are used for online transactions is two-factor authentication. This is a security measure that requires the user to provide two forms of identification before completing a transaction. For example, the user may be prompted to enter a password and then verify their identity through a unique code sent to their mobile phone.
Another control is the use of alerts and notifications. Banks may send notifications to account holders via email or text message whenever a transaction is made using their debit card. This allows account holders to quickly identify and report any unauthorized activity.
Additionally, financial institutions may offer fraud protection services to their customers. These services monitor transactions for suspicious activity and may automatically block or investigate any transactions that appear fraudulent.