I'll give you a question, please answer with step-by-step reasoning process.
Performing at her sales job was tiring, no matter how she felt she had to put on a big what?\nOptions:\n- persona\n- smile\n- laugh\n- act\n- singing

smile
People tend to mask their emotions during work.

Sales is a type of job where one needs to interact with customers.

Salesmen and women are trained to smile while talking for a pleasant customer experience.

.

The answer is smile