Answer:
true ameoba is unicellular
The spinal cord and the brain make up the central nervous system, and spinal cord nerves carry most messages between the brain and the rest of the body.
The vagus nerve carries the signal from the brain to the heart.
C.
Biotic mean alive, so we can cut off the first 2 easily. Aquatic birds eat frogs, so that one is safe for now. A decrease in something parasitic usually helps the population, so D is out too. The only one left is C.
Calcium which is a major mineral in the body
The spiders that survived the first pesticide spraying were resistant to the pesticide and when they reproduced most of their offsprings got the gene of pesticide resistance.
