Carbon dioxide in the atmosphere, which is mainly a result of mankind's burning of fuels, is thought to act like the glass of a greenhouse. It attracts heat radiation from the earth and its atmosphere, heat that otherwise would dissipate into space. The possibility that the greenhouse effect could change the earth's temperature has been discussed for many years. Scientists have agreed that carbon dioxide is increasing but there has been uncertainty about whether temperatures are also increasing. The chief difficulty in accepting the greenhouse effect has been the absence of observed warming match with the historic, that is, previous CO2 increase.
Which of the following words is restated in the passage?
a. historic
b. radiation
c. absence
d. temperature
آیا گزینه a پاسخ درست تست است؟