The word "issue" in the last paragraph can be replaced as _________.

A．they think that carbon is beneficial for plant growth
B．they want to use more fuels that can emit carbon dioxide
C．they think carbon dioxide is not the main reason for global warming
D．they think it will destroy the natural balance of gases in the world

A．People are better described in cold, objective terms.
B．The difficulty of getting to know a person is usually underestimated.
C．One should not judge people by their appearance.
D．One is usually subjective when assessing other people’s personality.