I believe this problem have these following choices:
5,000 cal
0.05 cal
5 x 10^3 cal
5 x 10 ^4 cal
Now 1 kilocalorie = 1000 calories, therefore:
50 kilocalories * (1000 calories / 1 kilocalorie) = 50,000 calories
Since there are 4 zeroes, so the scientific notation is:
5 x 10 ^4 cal (ANSWER)