The correct options are
A Human unhappiness is due to selfishness.
B Simple living is necessary for a happy life.
C Nature is to be respected.
Lao posited that the cause of human unhappiness in this world is human selfishness. A selfish person has unlimited desires which are not possible to be fulfilled. And therefore it eventually brings unhappiness. According to Lao, when humans acquire knowledge, they no longer remain innocent. Because, by applying such knowledge, humans built-up urban civilisation, rules, and regulations that are violated by themselves. And eventually, humans find themselves in an unhappy state. Therefore, the ideals of Lao look for a simple and natural state of human life.