Correct Answer: Abruptly

Solution : The correct choice is the second option.

Gradually means to change or progress slowly over time, while abruptly means suddenly or unexpectedly. They are opposite in terms of the speed or manner of change.

The meanings of the other options are as follows:

• Constantly : Continuously occurring without interruption.
• Readily : Quickly and easily.
• Steadily : In a stable and unchanging manner.

Therefore, the correct answer is abruptly.