Ineed
what is the first step necessary to begin setting up a website once a host has been selected and paid?
a. select a domain name
b. configure email addresses
c. upload website files to the host directory
d. log on to the website host control panel

d. log on to the website host control panel

Explanation:

The first step necessary to begin setting up a Website is to log on to the Website host control panel.  Technically, you could in many cases begin by uploading your files through FTP without the need to access the control panel, but the question asks about setting up a Website, that involves more than just uploading the files.

The other answers are good too, but not the first step to do:

a. select a domain name : Normally, that would have been done before, as you opened your account with the host, you would define the domain name before paying.  Since the question says you already paid, the domain must have been selected already.

b. configure email addresses : This is done through the control panel... so you have to go to the control panel first.

c. upload website files to the host directory : Although the files could be uploaded by FTP, which could be done without ever accessing the control panel,  the way most users will do it is through the control panel.  Also, you'll need to go to the control panel to configure the FTP accounts, since that is not always done for you.