The most appropriate response based on the experiment and the situation described is:
B White T-shirts did not absorb as much sunlight as dark T-shirts. White T-shirts did not absorb as much sunlight as dark T-shirts.
This response explains the difference in sensation between Billy and the girls. Billy's dark navy T-shirt absorbed more sunlight and heat, making him feel hotter, while the girls' white T-shirts reflected more sunlight, keeping them cooler. This aligns with the concepts of radiation and absorption covered in their class.