The F2 offspring of a cross would follow the ratio of 9:3:3:1 only if the cross is a <u>dihybrid for two unlinked traits</u>.
There is nothing like a monohybrid cross for two traits. A cross involving two traits is a dihybrid cross. Hence, options a and b are out of the equation.
A dihybrid cross for two closely linked traits would produce F2 offspring in another ratio that is different from 9:3:3:1 depending on the linkage map.
<em>Hence, the correct option is</em><em> C</em><em>.</em>
Homeostasis is maintained at many levels, not just the level of the whole body as it is ... Of course, body temperature doesn't just swing above its target value