Correct Answer: rigid

Solution : The correct choice is the fourth option .

Flexible is used to describe something that can easily be bent.

Rigid is something that does not lose its shape, even with the application of force. This makes it the correct antonym of the given word.

The meanings of the other options are as follows:

• Elastic is used to describe materials that are able to stretch and return to their original shape.
• Ductile is the property of being able to be drawn in thin wires.
• Pliable means the same as flexible.