Using SQL$,$ count how many classes each customer has signed up for. Show the customer's last name, first name, and number of classes. Use an appropriate JOIN.

a$.$ SELECT LastName, FirstName, Count$($ReservationID$)$ AS $[$Number of Classes$]$

FROM Customers INNER JOIN Reservations ON CustomerID $=$ CustomerID

GROUP BY LastName, FirstName;

b$.$ SELECT LastName, FirstName, Count$($ReservationID$)$ AS $[$Number of Classes$]$

FROM Customers INNER JOIN Reservations ON Customers.CustomerID $=$ Reservations.

CustomerID

GROUP BY LastName, FirstName;

c$.$ SELECT LastName, FirstName, Count$($ReservationID$)$ AS $[$Number of Classes$]$

FROM Customers INNER JOIN Reservations ON Customers.CustomerID $=$ Reservations.

CustomerID;

d$.$ SELECT LastName, FirstName, Count$($ReservationID$)$ AS $[$Number of Classes$]$

FROM Customers OUTER JOIN Reservations ON Customers.CustomerID $=$ Reservations.

CustomerID

GROUP BY LastName, FirstName;