Problem: Two sister cities used different methods to produce electricity. London used fossil fuels, while Edmonton use entirely hydro power to generate energy. Which city causes more acid rain?

A: London

Problem: Two farmers tried different methods of growing their crops. Nate used pesticides, while his buddy Don used bacterium that produces a toxin instead. Don was happy with the results. Which farmer didn't use a bacterium that produces a protein that can act as an insecticide?

A: Nate

Problem: Two brothers liked natural sciences. Ben decided to study Ecology, while his brother Dan decided to study Geography. They studied a lot and became very good at these subjects. Which brother studied more living components of the habitat?

A: Ben

Problem: Two identical twin brothers go to the doctor to get blood work done and also checked for STDs as part of their routine medical checkups. Neither man thinks they have caught anything, but both are sexually active so they want to get checked out. After getting the test results, the doctor tells Hank that he has strep throat, but no STDs. Jacob is told that he has hepatitis B. The doctor gives both men information about what medication to take and what they need to do to manage their diseases. Which man is more likely to have gotten a hepatitis B vaccine?

A:
Hank