Answer:
C. Concentration gradient
The reason why good sanitary practice should be observe and done especially in terms of washing dishes immediately after a meal in order to prevent bacteria from going and by this, it makes the enviroment more clean and more safe to people to live in. It is because when plates or used utensils are not cleaned after having it used, bacterial growth could sprout, making the environment dirty and dirt could interfere with someone's health into having them acquire illness that would also affect not only one person but also other people living in the house. That is why good sanitary practice is observed, not only because it promotes cleanliness but it is also because for the better health of the individuals.
Once the rock has been weakened and broken up by weathering it is ready for erosion. Erosion happens when rocks and sediments are picked up and moved to another place by ice, water, wind or gravity. Mechanical weathering physically breaks up rock. One example is called frost action or frost shattering.
Archaea bacteria live and thrive in extreme environments (extreme salt, extreme temperature), whereas eubacteria live best in more 'normal' environments that are closer to what we (humans) are used to.