Answer:
A. Create a custom object tab.
Explanation:
The custom object refers to an object in which a person creates to store the data and information i.e relevant for the business organization
While the custom object tab is a tab in which the data stored is displayed in the records of the custom object
Therefore according to the given situation, since the sales teams used the mobile app and want to create new insight records by using their phones
So for meeting this we should recommend creating a custom object tab