DNA- Deoxyribonucleic Acid is a molecule composed of two chains or double strands that coil around each other forming a double helix to carry the genetic information for the development of an organism.
<u>Explanation:</u>
- DNA contains the information that instructs a living organism to develop, grow, survive and reproduce.
- The information instructed is found inside every cell and is passed down from parents to their children.
- DNA is made of nucleotide molecules which in turn contains a phosphate group, a sugar group, and a nitrogen base.
- Deoxyribose in DNA is another form modified from ribose sugar.
D) The Earth was hit by a one or more objects from space 65 million years ago. The iridium layer shows an extraterrestrial cause for the extinction at the Cretaceous Tertiary boundary, discovered by the Alvarez family. The first discovery of this layer was in the Bavarian alps, in Lattengebirge. The Alverez family proposed that the extinction of the dinosaurs was due to a large meteor hitting the Earth at the end of the Cretaceous period, marking the KT boundary with this clay layer which has a high content of iridium. Iridium is not common on Earth, but is common in meteors.
...........The answer is A
