One should never be reckless in his dealings with others.

The correct answer is: B. careful

Reckless means acting without thinking or caring about the consequences. It is the opposite of careful. A careful person is cautious and takes steps to avoid harm or danger. They are also considerate of others and their feelings.

The other options are incorrect because they do not mean the same thing as careful.

• Indifferent means not caring about something or someone.
• Imprudent means acting without thinking about the consequences.
• Lenient means being forgiving or not strict.

It is important to be careful in our dealings with others because we can easily hurt them or ourselves if we are not. We should always think about the consequences of our actions before we do something. We should also be considerate of others and their feelings.