Answer:
D. All of the above
Explanation:
A positive feedback loop is not "positive," at least in the way one is inclined to think about it. In other words, it is not always beneficial. A positive feedback loop simply means that it brings about and induces a response or product being produced continually, typically bringing it away from a state of homeostasis (where everything is balanced) called a set point. If we look at choice A we see that after a glacier melts, it shows less white surface. This causes more melting. Then once more melting occurs, there is even less white surface, causing even more melting. This is an example of a positive feedback loop; it is amplifying the response.
Let's look at Choice B. It says that as plants grow, their litter creates more soil humus, which makes it more hospitable for other plants. When, in this case, as the <em>other</em> plants grow due to humus, then in turn will release their own litter while growing. The response here, once again, is amplified.
Let's look at choice C. It says violence breeds more violence. If someone were to attack another person, that person would respond with violence. Then the person who originally caused the violence would respond with even more violence. Here, the action is being amplified as well.
Therefore all choices are examples of positive feedback loops!
