4. Which of the following statements is true about aquaculture?
A. An aquaculturist can throw some young shrimp in a pond, and they will take care of themselves
B. It means "cultivating small acreages of land."
C. An aquaculturist must tend to the tanks carefully to make sure predators do not eat the shrimp.
D. The tanks are large aquariums built in warehouses

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

a corroding iron, if that's one of your choices