Both molecules and compounds are made up of . Two or more atoms joined together by shared electrons form . Substances made from two or more different elements are .

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate

the last one: artificial selection/genetic engineering

plant breeding is modifying the genetic composition of the plant - but this isn't cloning (which is specifically introducing a gene into a genome). but you are artificially selecting for the phenotype that you want.

the second one is literally genetic engineering - the gene would have been cloned first and then inserted or genetically engineered into the new plant cell (the cotton).

the correct answer is anaphylaxis.

anaphylaxis is a condition caused by insect bites, foods, medications, manifested by tongue swelling, shortness of breath, vomiting, low blood pressure. it sometimes may occur without an obvious reason. it is treated with epinephrine injection.other tretments include antihistamines and steroids,