Why You Need Baking Powder

I was rushing to make a number of dishes and bake cookies and other goodies before we had visitors. I started whipping up lemon poppy seed loaves at 10pm—not a good idea. The loaves looked fine when I took them out of the oven, but within minutes they had shrunken to become dense and brick-like. Instantly I realized that I had left out the baking powder: luckily I was too tired to get upset with myself. The next morning I baked two perfect loaves in no time.

Guess which one is missing the baking powder?