The app builder should use three features to meet the business requirements:

Process Builder: This is a type of automation tool that can execute actions based on certain criteria. In this case, the process builder can have a criteria that evaluates if an opportunity is in the Secure Commitment Stage, and then execute an action that submits it for approval.

Apex: This is a programming language that allows developers to execute complex logic on the Salesforce platform. Apex can be used to create triggers that run before or after certain events, such as insert, update, delete, or undelete of records. In this case, Apex can be used to create a trigger that runs before an opportunity is updated and submits it for approval if it is in the Secure Commitment Stage.

Flow: This is another type of automation tool that can guide users through a series of screens and perform actions based on user input. Flow can also be triggered by certain events, such as when a record is created or updated. In this case, Flow can be used to create a record-triggered flow that runs after an opportunity is updated and submits it for approval if it is in the Secure Commitment Stage. Option A and D are not features that can meet the business requirements.