The app builder should use two options to ensure all contracts route for the correct approval and also prevent the sales rep from making changes to the record while it is being approved:
Create an approval process on the Contract object with criteria set on a second approval step set as 'Amount__c > 10,000' and set the approver as director. An approval process is a type of process that automates how Salesforce records are approved in an organization. An approval process can have multiple steps with different criteria and approvers. In this case, the app builder can create an approval process on the Contract object with two steps: one for the sales manager approval and one for the director approval if the contract amount is over $10,0001.
Create a validation rule on the Contract object that prevents updates to the contract record while it is being reviewed. A validation rule is a type of rule that checks data quality by verifying that the data in a record meets certain standards before it can be saved. A validation rule can prevent users from making changes to a record that is in a certain status or stage. In this case, the app builder can create a validation rule on the Contract object that prevents updates to the contract record if its Approval Status field is not equal to Not Submitted2. Option B and D are not options that can ensure all contracts route for the correct approval and also prevent the sales rep from making changes to the record while it is being approved.