What could have caused this?

Entering the New Year with a fall to my face as i enter the office, left me with a mark on my forehead as my forehead knocked the tiled floor.....
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To be precised, as i walked and slipped, in efforts to regain my balance, i tried to grab hold of surroundings. In a split second, my body reached neared the floor and i saw the white tiles inches away from my face. At that split moment, all i could imagine was the damage it may have caused to my face. At that point, i blacked out for a second and thought this is it....

Suddenly i felt my hand pushed a little and when my eyes opened, i was sitted upright. In a daze, i felt my wrist sore. A new experience for a New Year?

To my colleagues' amusement, this location has been named by one as the crime scene.
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Now..the question is...having knocked my forehead to the smoothed surface flooring, what could have caused this marking.....

A. My handphone - samsung edge
B. The access card

C. A starbucks take-away plastic cup with straw
D. Some particles or the gaps between the tiles

For I am no forensic expert, please do share your thoughts........