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.