Discovering the joy of primes

I am really enjoying my 50 f1.8

I am amateur. Have been using the kit lens for a while, and still looking for a good replacement walkabout. used to think zooms were everything, but the 50 f1.8 showed me what joy a simple honest prime can do.

I am submitting some pics for a basic photography course assessment soon. I can't decide which pic is better. Please give me your opinions (try to be gentle...it's just a basic course!) which one I should submit (or not at all). The pics were cropped from an original, and they are unposed.

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http://www.pbase.com/mhlau