I'm not sure, but I think it would be mud.
Absorption of heat by breaking down hydrogen bonds
When Charles Darwin considered wings of birds, apart from his famous proposal he also predicted that fossils will be found with structures that are intermediate between early and modern form.
Answer: Option C
<u>Explanation:</u>
Charles Darwin was basically referring to transitional Fossil while considering Wings of bird. So what are transitional fossil? They are the fossil remains of both the ancestral group and the descendant group.
Since we don’t have enough record of the fossils, it is very difficult to know the accuracy of transitional fossil. However, we do have some record of fossils from which we can gather enough evidence of how the fossils where earlier and how it evolved over a period of time.
2 is crescent and 4 is gibbous
