Correct Answer: madness

Solution : The second option is the correct answer.

Madness is the most fitting choice, as it encompasses the state of being mad.

The meanings of the other options are as follows:

• Happiness means a positive and joyful emotional state.
• Calmness is a serene and tranquil emotional state in the absence of disturbance.
• Sadness is a negative emotional state characterised by sorrow or unhappiness.

Therefore, the complete sentence is: Either he is mad or he feigns madness.