How can you tell which elements are more metallic than others by just looking at the periodic table?

You can tell just by looking which elements are more metallic than others because there's a zigzag line dividing metals and non metals in the periodic table. It depends on the number of electrons. If there are more electrons, the stronger the metallic bond.     

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.