She stumbled at the stone and fell _____ a ditch.

She stumbled at the stone and fell _____ a ditch.

Explanation

Stumble means ٹھوکر کھانا

Stone means پتھر

Ditch means کھائی 

Fell into something means کہیں گر پڑنا

We use into to refer a motion.

Into is a preposition here.