Read the following article and mark the letter A, B, C, or D to indicate the correct option that best fits each of the numbered blanks from 1 to 6.

Urban heat islands
Scientists now fear that global warming may be connected by what they call the ‘urban heat island effect’. This refers to (1) __________ rises in temperature in big cities, when compared to surrounding rural areas, that affects local climate patterns (2) ________ rainfall and wind. Basically, when plants and trees are cut down and concrete is put in their place, the natural state is already altered. Then the way the concrete itself absorbs, stores and releases heat further alters the natural balance. Then waste heat from traffic and buildings, together with ozone pollution, contributes still further (3) __________ the problem.
Scientists claim it is important to (4) __________ action to counter this effect in cities – by planting as much vegetation as possible. In addition, they are urging city developers to use a more expensive concrete for pavements (5) __________ rainwater, thus cooling them down. They also advise that rooftops and pavements should be made of light-coloured (6) _________, as dark objects convert energy into heat whereas white objects reflect light.
(Adapted from First Trainer)