Why is a dominant allele called dominant

The correct answer is option A which is, "it dominates the phenotype".

There are two types of alleles in the gene pair of one trait.

One is known as dominant allele while other is recessive allele.

One allele is dominant over the recessive and when both alleles come together, the dominant allele will describe the phenotype.

But not always, as in case if both alleles are recessive then recessive allele will describe the phenotype.

Hence the most relating statement is option A.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.