Correct Answer: migration

Solution : The correct choice is the fourth option.

In the context of the sentence, immediate relocation suggests the urgent need to move to a different place promptly. Migration aligns closely with this idea, as it denotes the act of moving or relocating.

The meanings of the other options are as follows:

• Emergence denotes the process of becoming visible or coming into existence.
• Ending denotes the conclusion or termination of something.
• Expiration denotes the end of a period of validity or the act of breathing out.

Therefore, the correct answer is migration.