Aditya is talking with a woman he wants to ask on a date. He wants to make sure that she likes him before he asks, so he watches the way that she smiles. Aditya figures that if she displays a genuine smile, not a fake one, it is more likely that she feels positively towards him and will agree to go out with him. Aditya is happy when he finally sees a genuine smile, where

she showed her teeth.
the muscles on her face made her cheeks move up.
there were small crinkles at the corners of her eyes.
the corners of her mouth moved up

There were small crinkles at the corners of her eyes.

Explanation:

Duchenne smile, also known as genuine smiles, was named after the French Neurologist. The name of this French Neurologist was Guillaume Duchenne de Boulogne. He studied the facial expressions in the nineteenth century in which he discovered that a genuine smile can be identified by observing two things.

He asserted that when a person smiles genuinely, two facial muscles are involved namely, Zygomatic major muscle and Orbicularis oculi muscle.

So, according to the theory of Duchenne smile, a genuine smile will have a cheeks lifted and a natural crinkle around the eyes.

So, the correct answer is the third option.

its d i know cause i've been googling it