digital logic - Binary number 11 represents?

I was going through some of the questions in my textbook and I got stucked up here. Kindly help me with this

The Binary number 11 represents __

   1) -3 in sign magnitude and -1 in 2's complement
   2) 7 in sign magnitude and -1 in 2's complement
   3) -3 in sign magnitude and -3 in 2's complement
   4) 7 in sign magnitude and -3 in 2's complement

The answer was 'c'. But I am unable to figure out the reason why and I cant even trust it because I am unable to judge the answer. Please help me with these. Thanks