What are the requirements to get into National University of Singapore (NUS) Psychology?

Okay, so I checked nus's web and they said that a minimum grade of c6 in math 'o' levels...what I don't understand is, do I need a diploma in polytechnic or at least an 'a' level? I'm in poly now but my grades are not fantastic and my course do not really have a relation to psychology (I'm in life science)...so is my 'o' level certain all I need to get in? Thanks in advance!!!!