A: Changing the Lead Matching Rule to 'Block on create' will directly prevent duplicates at the point of lead creation based on defined criteria.
Reference:
Salesforce Help - Duplicate Management

Groups is available in the Chatter section of the navigation menu, not in the selected list for the navigation menu. According to the Salesforce documentation, "Groups appear in Chatter, not in Navigation Menu." Groups is not available in the recent section of the navigation menu, nor is it included in the Smart Search items but unavailable on the navigation menu. Groups is unavailable in the selected list for the navigation menu.

The best way to solve this problem is to filter components by device using Form Factor. Form Factor is an attribute that can be applied to components on a Lightning record page to control their visibility based on the device type, such as desktop, phone, or tablet. By using Form Factor, the app builder can hide some components that are not relevant for mobile users, such as charts or reports, and show only the components that are necessary for data entry, such as fields or actions. This way, the mobile users do not have to scroll through all the components and can enter data more easily. Reordering the fields may not solve the problem completely, as there may still be too many components on the page for mobile users. Updating the training documentation may not help either, as it does not address the root cause of the problem, which is the layout of the page. Deselecting the phone radio button on the Lightning record page assignment may not be desirable, as it will prevent mobile users from accessing the record page at all, which may affect their productivity and functionality.

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.

A flow is a powerful automation tool that can perform complex logic and data manipulation. A flow can be used to delete rejected quotes by using a record-triggered flow that runs when a quote is updated, or by using a scheduled flow that runs at a specified time.