Which detail best demonstrates discourse between characters?

excerpt from A Good Place for Maggie
by Ofelia Dumas Lachtman

“ACCIDENT AT GREENSTON NUCLEAR PLANT, No Danger to Community, Officials Say.”

Every time that headline from yesterday’s Los Angeles News flashed into her mind, Margarita—Maggie—Cruz griped the steering wheel of her VW more tightly and assured herself that she was doing the right thing. It wasn’t as if she were in danger from the Greenston plant in the desert hundreds of miles away, but those headlines had been the convincing factor in her decision. Yes, it was the right thing to do, and hour after hour as she drove north of Los Angeles, she had felt more and more competent and more secure. Until now.

For the last hour she had been so intent on the changing countryside that she forgot to buy gas. The gauge said empty. She drove on, dreading the moment when the motor would draw on the last drop of gasoline and give up. She was driving on a narrow country road lined with tall eucalyptus trees and nothing else. Then in a clearing on the left side of the road, she saw a battered old sign with faded red letters: G-A-S. No, it wasn’t a mirage; it was more like a miracle. With a grateful sigh she turned into the run-down station, bumping over broken concrete and coming to a stop by one of two pumps.

A weary-looking old man in grease-spotted overalls appeared beside her. "Fill 'er up?"

“Is it cheaper if I pump it myself?” It didn’t look as if he’d take a credit card and she was low on cash.

“All the same here, missy,” the man called, rounding the car. “Fill ‘er up?”

Maggie said yes, please go ahead, and climbed out of the blue VW. Good thing I didn’t splurge on lunch, she thought, staring at the pumps. Gas is almost twice as high up here as it is in Los Angeles. But I’m not complaining. When she had driven mile after mile without finding a gas station, she had begun to think that maybe being sixteen and a half didn’t make her that smart; maybe a trip like this was a little much for her. Now she felt better. She stretched and thought, Dad would be proud of me. I’m doing what is right for me. Oh, I’ll miss my friends, especially Mim and Lorena. I’ll even miss Ryan. I wonder if he was really going to ask me to the TGI June bash? Well, that’s history. Now is now.