Nikon d3100 only has two autofocus choices why?

I just received my nikon d3100 and i'm trying to change my auto focus to AF-C but when i goto the menu it only shows two option AF-A and MA
Please Help
thank you

Added (1). Thank you i changed it to M and it worked =D

You should have 4 options for focusing including MF, switch to M mode and check again, you might have a defective camera, when I got my D3100 out of the box it took blank pictures and I had to return it for a new one

Read the Guide! Maybe by reading it, you will master the settings of Nikon D3100.

What drive setting do you have on?

AF-C may only work when in continuous shooting mode.

Make sure that out of the 4 AF area modes you select Dynamic Area. It should work in this mode.