How do hot fluids act in metamorphism? .

Hot fluids interact with the preexisting rocks or crystallize and precipitate the minerals.

Explanation:

Metamorphism is the change of the structure or composition of a rock by pressure, heat, or other natural agency. Hydrothermal metamorphism occurs chemically active when hot, hydrothermal fluid or solution interact with surrounding preexisting rock.

The magma or hot fluids crystallizes the hydrothermal solution is driven off into the surrounding rock where it exudes into pores and cracks precipitating the minerals.

In oceanic hydrothermal metamorphism magma drip out onto the ocean floor to form pillow Basalts.

a bird that nests only in a particular tree species.

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).