Prof. Preney spent a considerable amount of time discussing provided project code because $($select all that apply$)$:

Question $5$Select one or more:

a$.$

Since the project code is required to have all CSS and Javascript code referred to in the "head" tag of any generated HTML page instead of embedded such within various portions of the HTML page sent to the browser, the provided code enables achieving such using an object$-$oriented hierarchy.

b$.$

Code that demonstrates how to encapsulate $($e$.$g$.,$ "hide"$)$ the internals of calls using classes.

c$.$

Web server code needs to determine what the response to an HTTP request is first because if there is an error generating the response an error needs to be sent as the reply instead of what was requested and one cannot output anything until one knows there is an error or not.

d$.$

Code that demonstrates how to make use of a database server.