Two options that the administrator should check to ensure the product is available are:
Confirm the correct price book is selected on the opportunity. A price book is a list of products and their prices that can be added to an opportunity. An opportunity can have only one price book at a time, and the products that are available for selection depend on the price book that is chosen. Therefore, the administrator should check if the opportunity has the right price book that contains the new keyboard product.
Ensure the product is associated with the correct price book. A product is a good or service that can be sold in Salesforce. A product can be associated with one or more price books, depending on how it is priced for different markets or segments. Therefore, the administrator should check if the new keyboard product is added to the appropriate price book that is used by the opportunity.
The other two options are incorrect because:
Making custom fields does not affect the availability of products on an opportunity. Custom fields are used to store additional information or calculations on an object, but they do not determine which products can be selected from a price book.
Turning on field tracking does not affect the availability of products on an opportunity. Field tracking is used to monitor changes to certain fields on an object and display them in a history related list, but it does not determine which products can be selected from a price book.

Salesforce Authenticator is an app that allows users to verify their identity when logging in to Salesforce using two-factor authentication (2FA). 2FA adds an extra layer of security by requiring users to enter a verification code or approve a notification on their mobile device after entering their username and password.
To look at how many users have successfully used Salesforce Authenticator since it was rolled out, an administrator can use two ways:
A) Run a session setting report, specifying login methods by user.
A session setting report is a report that shows information about users' login sessions, such as login time, location, IP address, browser, platform, etc. A session setting report can also show the login methods used by users, such as password, verification code, or notification. By running a session setting report, specifying login methods by user, an administrator can see how many users have used Salesforce Authenticator to log in to Salesforce. Reference: https://help.salesforce.com/s/articleView?id=sf.reports_session.htm&type=5 C) Create a new view in Identity Verification History, specifying Method.
Identity Verification History is a page that shows the history of identity verification attempts for each user in the org. Identity verification history includes information such as date, time, status, method, and IP address of each attempt. By creating a new view in Identity Verification History, specifying Method as a filter criterion, an administrator can see how many users have used Salesforce Authenticator to verify their identity when logging in to Salesforce. Reference: https://help.salesforce.com/s/articleView?id=sf.identity_verification_history.htm&type=5