Correct Answer: destroy

Solution : The fourth option is the correct choice.

Destroy is the most appropriate synonym for efface in this context, as it means to eliminate or erase.

The meanings of the other options are as follows:

• Reveal means to make something known or visible, which is the opposite of efface.
• Clarify means to make something clear or understandable, not to erase or remove.
• Maintain means to keep something in a particular state or condition, which is different from removing or erasing.

Therefore, the correct sentence is: In order to protect his identity, the spy had to destroy all evidence of his true name and occupation from his personal documents.