Answer:
Density is nearly 3 cabs per hectare
Explanation:
Given -
There are three three intertidal regions.
Area of each intertidal region is
hectares.
Number of crab in the intertidal regions are as follows -
Intertidal region I - 7
Intertidal region I - 2
Intertidal region I - 6
Sum of crabs in all three regions is equal to

Total area of all three intertidal regions is equal to
hectares
Now density per hectare is equal to total population of crab divided by total area of all the three intertidal regions
Density 
Density is nearly 3 cabs per hectare
Answer: The Answer is A.) Burning of fossil fuels
Explanation:
Answer:
C. Cytology is the study of cells, while histology is the study of tissues
Explanation:
Just learned about cytology, and searched up histology, and it is about tissues. Every other answer is wrong.
Hope this helped :)
Answer is a. neolithic where they use wild and domesticated crops and domesticated animals