In the chemical reaction below, calcium metal and water react to form calcium hydroxide and hydrogen gas. calcium metal + water → calcium hydroxide + hydrogen gas

Calcium and water are the reactants in this chemical reaction, whereas calcium hydroxide and hydrogen gas are the products that are formed. Once the reaction reaches completion,
A.
the total mass of the products will be greater than the original mass of the reactants.
B.
the total mass of the products will be equal to the original mass of the reactants.
C.
the total mass of the products will be less than the original mass of the reactants.
D.
the products of the reaction will have changed back into the reactants.

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.

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).