Correct Answer: Offense

Solution : The correct option is the first option.

Explanation:
The most appropriate synonym for indignation is offense as both words convey a sense of being upset or angered by something perceived as unjust or unfair. Offense means a feeling of anger or resentment caused by a perceived injustice or insult.

The meanings of the other options are as follows:

• Designation refers to the act of assigning a particular name, title, or role to someone or something.
• Resignation means either the act of formally quitting or stepping down from a job or position.
• Defense refers to the action of protecting oneself or something else from harm or danger.

Therefore, the correct answer is offense.