Bottom Pinstripe

What to wear to drug test at hospital?

I'm getting a job at concierge in a hospital and I have to go in for a drug/TB test tomorrow. I don't know what to wear! I know not to go in looking too casual, but I don't know what pants to wear. The choices are: dark jeans, black pants (but the fabric's thick and has a sort of pinstripe pattern. the bottom of the pant leg flares out pretty wide and they're kinda on the long side), and grey plaid pants with thin fabric. Any ideas for shirts, too?

I would wear dark jeans and a really nice top, like something silky or a printed tank with a short sleeved cardigan over it. Wear cute sandals, but not flip flops.

Original Pinstripe track