The author raises issues that would most concern which of the following groups

A．compare skyscrapers with other modem structures
B．describe skyscrapers and their effect on the environment
C．support the use of stone in the construction of skyscrapers
D．illustrate some architectural designs of skyscrapers

A．Reminding people the benefits of exposure to sunlight.
B．Warning people against the danger of too much sun.
C．Advising people to spend more time in the sun.
D．Improving skin conditions.