Answer:
A. chromosomes
Explanation:
Chromosomes are structures found in the center (nucleus) of cells that carry long pieces of DNA. DNA is the material that contains genes and is the building block of the human body.
Chromosomes come in pairs. Normally, each cell in the human body has 23 pairs of chromosomes (46 chromosomes in all), of which half comes from the mother and half from the father.
Glucose is the main provider of energy for the brain and the nervous system. Because the brain is so rich in nerve cells, or neurons, it is the most energy demanding organ, using one half of all the sugar energy in the body. Brain functions such as memory, thinking and learning are closely linked to glucose levels and how efficiently the brain uses this fuel source.
Primary succession occurs in an area that has not been previously inhabited by a community. Places where primary succession occurs include newly exposed rock areas, sand dunes, and lava flows.
This is true, comets have long, indefinite life spans.
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