Choose A: their strong people have said the wrong thing, make strict era.By their weak person bullied, will do good."Cruel" index is moderate.

B: peace, peace, such as the spring breeze, but is very hard on yourself, cruel, is worth relying on.

C: good at hiding themselves, but once the contact with the opposite sex, it will came clean about the inner world, sometimes use hard words, but the cruel relation with their personality.(Psychological tests /test/)

For survival, life and many things choose D: think of before the end, want to more, not to relax, as "cruel" to themselves and others.