<span>a. a substance that is naturally found in the brain</span>
Answer: water and light
Explanation:
Abiotic factors are non living things that affect biotic factors for an example plants need water and sunlight to live which are abiotic factors
The correct answer is T helper cells. <span>T helper cells are important because they have the ability to stimulate other cells to kill the foreign particles (viruses, bacteria, fungi, parasites).T helper cells help other cells in the immune response by recognizing foreign antigens and by secreting cytokines that then activate T and B cells.</span>
But anyway, the solution to our problem, the answer to our question is that the stages of stellar evolution, in the correct order, are: a nebula followed by a protostar followed by a main sequence star followed by a red giant and then finally, a white dwarf.