Final answer:
Drive degaussing is the most thorough method to erase data on old PCs, especially in a sensitive environment such as a bank, ensuring complete data destruction.
Step-by-step explanation:
The most appropriate method for erasing the data on old PCs in a bank environment is Drive Degauss. This process involves using a machine that generates a strong magnetic field to disrupt the magnetic data on the hard drive platters, rendering the drive completely unreadable. This ensures all sensitive information is irretrievably destroyed. Standard format and Quick format methods do not erase data completely as they leave information recoverable with data recovery tools; changing the jumpers on the hard drive will not erase the data at all but simply alter the way the drive communicates with the motherboard.