Answer:
a. iris
Explanation:
iris is actually the structure of the eye that regulates the amount of light passing to the visual receptors of the eye
The secondary succession is triggered by a natural event (forest fires for example) that destroys an established ecosystem. The destroyed forest will then undergo a regrowth process. This secondary growth may look bizarrely different from the way how the original forest used to look like. There are several stages involved after the forest os being burned. The first stage involves the colonization of massively burned places by plants and fungi. The following stage starts when minuscule plants such as grasses dwell in the forest. And then, huge plants that require lots of direct sunlight will move in. Lastly, new trees will continuously grow up to a point where they makeup a forest that remains in time except there are major interventions.
Honestly, this is supposed to be your opinion, but I will give you mine. I think there should by far be a quality standard, that they should always provide good quality things. It all just depends on what kind of standard they are talking about or what the question is referring to. If there are experiments going on, there should definitely be a certain standard of safety and ensure that the person would come out alive. I hope that this could help a bit, and I apologize if this was not the type of standard in which you were looking for. If you need further help, you can send a DM my way and I will respond when I get the chance. Have an amazing day!