I think it's D. Sry if you get it wrong though
Background extinction refers to the normal extinction rate. These are species that go extinct simply because not all life can be sustained on Earth and some species simply cannot survive. Mass extinction is a widespread event that wipes out the majority (over 50%) of living plants and animals.
I think the correct answer from the choices listed above the first option. In a polar covalent bond, the distribution of common electrons are <span>not shared evenly due to a greater positive charge from one atom’s nucleus. Hope this answers the question. Have a nice day.</span>
The right answer is: vitamin C and choline
Choline (vitamin B4) is the precursor on the one hand acetylcholine (important neurotransmitter and neuromodulator) and on the other hand, the cascade initiated by betaine (intermediate in the biological methylation and precursor of membrane lipids). In this, it is considered, by extension, as an integral part of the family of B vitamins,
Vitamin C protects against cellular aging, is essential for the immune defenses and increases the assimilation of iron of plant origin. It also contributes to the formation of collagen. Its deficiency leads to a disease called scurvy (hence the ascorbic acid name of vitamin C).
The stage that scientists begin to ask questions and attempt to explain observations is A. forming hypotheses. This is because a hypothesis is basically a testable question about observations scientists make.
