Answer: A. the customer checkout process.
Explanation:
A Process scope refers to the activities performed in one's job level that are necessary to transform inputs into output.
In the case of a Cashier at a supermarket, their job level requires them to take inputs ( good purchased by customers) and transform them to output (process customer payment) which represents the process of a customer checking out.
Their process scope therefore would be just that, the customer checkout process.