Which of the following is a duty of banks to customers?

The duty of banks to customers primarily revolves around ensuring the security and integrity of the customer's financial transactions. Highlighting attempts to forge signatures aligns with this duty as it reflects the bank's responsibility to protect customers from fraud and unauthorized transactions. By identifying and alerting customers to potential forgery, banks fulfill their obligation to safeguard their clients' assets and maintain trust.

In contrast, rejecting all payment orders would undermine the very purpose of a banking service, which is to facilitate transactions as per customer requests. Dictating customers' financial decisions is an overreach of the bank's role and contradicts the principle of customer autonomy in managing their finances. Similarly, investing customers' money without consent disregards the fundamental ethical requirement of obtaining customer approval and trust, potentially leading to legal ramifications and damage to customer relationships. Thus, the focus on fraud prevention through detecting forgery attempts clearly illustrates the bank's commitment to customer security and trust.