Please answer Part B$!$

$1)(10$ point question$)$ A group of scientists work with burrowing deer mice $($inbred lab strain$)$ that are adapted to living in the desert, and a related species of field mice that live in wheat fields and nest above ground $($also inbred strain$).$ The scientists were interested in nail length and ear size. All mice were raised in the same lab$-$controlled environment. They collected the data below from interbreeding populations of the two inbred lines to try to understand these two quantitative traits.