Will give ! read the excerpt from the evolution of useful things.

the new two-tone style of painting automobiles was popular in 1925, but it presented considerable problems for auto manufacturers and body shops alike. in order to get a clean, sharp edge when applying a second paint color, the first had to be masked, of course, and this required that newspaper or butcher paper be fastened to the car body. if shop-brewed glue was used, it would sometimes stick so well that it had to be scraped off, more often than not pulling paint with it. surgical adhesive tape was sometimes employed, but its cloth backing tended to absorb solvents from the newly sprayed paint and cause the masking materials to stick to the paint they were intended to protect. clearly, existing means of masking had serious flaws.
which statement correctly describes how the central idea of this excerpt is developed?
a. it is stated directly in the beginning of the paragraph and developed throughout.
b. supporting details are given before the central idea is stated at the end of the paragraph.
c. it is hinted at throughout the paragraph, but the reader is expected to figure it out.
d. it is revealed through a sequence of events and defined in the end of the paragraph.