<span>Sheet fractures are accurate fractures defining slabs of rock that range from 0.5 to 10 meters thick. They normally form in sets parallel to the Earth's surface but may form in convex-upward or concave-upward sets. The most popular hypothesis of the formation of sheet fractures is that they are the result of expansion and tangential fracturing consequent on erosion offloading or pressure release.</span>
Option D – amphibians may use their skin for gas exchange is the characteristic feature of amphibians that differs from reptiles.
Explanation:
The amphibian skin is moist, thin and marbled and supplied by blood vessels running on its surface. The moisture present in the skin dissolves the oxygen present in its surrounding which is absorbed by the blood vessels. Special glands help the amphibians to keep the skin moist.
The very thick and tough scales present on the reptiles prevent them to absorb oxygen through their skin. Hence, they breathe and respire through their lungs.
Amphibians have three-chambered heart. They do not develop amniotic eggs. Adult amphibians although spend much time on land, they breed only in water due to the absence of amniotic sac
.