C is your answer :)
And also C and D are true but its C.
This question is on Yahoo Answers
Answer:
Atoms are the basic units of matter and the defining structure of elements. The term "atom" comes from the Greek word for indivisible, because it was once thought that atoms were the smallest things in the universe and could not be divided. We now know that atoms are made up of three particles: protons, neutrons and electrons — which are composed of even smaller particles, such as quarks.
Atoms were created after the Big Bang 13.7 billion years ago. As the hot, dense new universe cooled, conditions became suitable for quarks and electrons to form. Quarks came together to form protons and neutrons, and these particles combined into nuclei. This all took place within the first few minutes of the universe's existence
Adenine, Thymine, Cytosine and Guanine.
<u>Explanation</u>
In double helix, the nitrogenous bases of opposite nucleotides form pairs through hydrogen bonds. The nitrogenous base adenine of one nucleotide forms pair with thymine of opposite nucleotide, while cytosine forms pair with guanine.
