I've noticed that many students get the wrong answer because they think too much! They worry about small differences in meaning. For example, look at the following part of a reading passage:
The two week planned study into the psychological impact of prison life...
Now decide whether the following statement is true, false or not given:
The study aimed to investigate the mental and behavioural effects of life in prison.
The statement is true, but many students put not given because they "over-think" the meaning of 'psychological'. They think that the definition of psychological must be more complex than 'mental and behavioural'.
Don't think too hard about small differences in meanings. 'Mental and behavioural' might not be a perfect definition of 'psychological', but the overall meaning is the same (a simple definition of psychology is the study of the mind and behaviour).