C. Ordinarily, you must specify method="post" with a relevant <cfhttpparam> tag to send variables. However, URL parameters can be sent in the URL attribute itself.
A2:
B. <cffile> is required to receive an uploaded file from a client browser. <cfftp> is used to manage a remote FTP connection and file transfer.
A3:
C. Header contains the headers sent back from the remote server. The other options are valid CFHTTP variables but will not contain server header information.