Color is how vivid, bright, or rich a color is.

The correct answer is a.the castrati were classical singers with very high voice equivalent to that of a soprano, mezzo-soprano or contralto. this effect of high voice was produced by castration before puberty or an endocrinological condition. the castrati first started signing at the church but then they also sang at the opera. they did not only sang in italy but in many churches in europe. finally, they were singing male and female roles as well. 

Answer:   a thesis statement is the subject of the whole paragraph and is a generality.
a thesis statement clears everything up. its located at the end of an introductory  paragraph  that  summarizes  the point of the essay in all just one or  two  sentences.