The correct answer is the third one
In this virtual lab, grow two species of paremecium in test tubes and record data on their population growth. Experiment shows that when grown together, one species will die, illustrating the competitive exclusion principle.
The obvious choice would be the hox gene.
Because while you're preagant your have so much presure on it it doesnt have a choice where as weight gain everything grows with it. Think of it this way, if you've ever felt a pregants womans belly its harder than usual. If you touch someones belly that is bigger its more smoshy (I know thats not spelt right)