Answer:
D.) both a and c
Explanation:
Past observations made early in history as well as telescopes and space probes are very important in studying our universe and galaxies.
- Space probes are increasingly gaining momentum as technological and scientific advancements are being made.
- Telescopes are used to see or picture objects that are very far away in space.
- Also, understanding the past records and historical data is essential for the study of the universe.
Microscopes are not used in galactic studies. They are only used to study the world of micro-organisms.
Answer:
When you eat, food passes from the throat to the stomach through the esophagus. A ring of muscle fibers in the lower esophagus prevents swallowed food from moving back up. These muscle fibers are called the lower esophageal sphincter
Explanation:
Amino acids. These class of compounds
are considered the building blocks of most organisms, and around 500 of these
are known and indentified. All proteins, carbohydrates, and nucleic acids are
polymers ("many units") and each unit is an amino acid.
