Puzzle 011: Which Direction Slopes Up?

ナゾ０１１　坂の上はどっち？
ここにある写真は坂道の様子を撮った
ものだ。
でも、カメラを傾けて撮ったので
道路は水平のように見えている。
さて、坂の上はどっちかわかるかい？
Ａ，Ｂいずれかのボタンを押して
答えよう。

Google Translate
Here are some photos I took in the hill state. But the road taken by tilting the camera so that the horizon looks like. Well, see you on a hill to roll one? A, B answer by pressing one button.

Notes on Puzzle
You're given a photo of two people on bikes passing each other. The photo was taken on a hillside, but tilted so the horizon appears flat. Using other visual cues, you have to figure which direction is uphill.