What should be excluded to prevent overwriting functionality during new promotions?

Excluding Apex Classes from the Auto-resolve field is essential during new promotions because these classes often contain critical business logic and functionality that, if overwritten, could disrupt application stability. Auto-resolve attempts to merge changes automatically, which could result in unintended consequences if there are conflicting updates in Apex Classes during the promotion process. By excluding them, you ensure that developers manually review and resolve any changes, preserving the integrity of the business logic that those classes encapsulate.

The other options do not address the direct risk of overwriting functional logic in the same manner. For example, while excluding Apex Triggers is important, the Manual Resolution process typically involves active review and resolution; therefore, it does not offer the same level of safeguard against overwriting critical functionality as excluding Apex Classes does. Layouts and Child Objects also may play a role in the deployment process but are less likely to directly impact the core functionality when compared to Apex Classes. Hence, the focus on class management through exclusion from automatic resolution is a crucial practice during promotions to avoid inadvertent overwrites.