Complete the following sentences with appropriate

单项选择题

Complete the following sentences with appropriate words in the box. Change their forms if necessary.

retain
biodiverse
sustainable
renewable
affordable
calamity
ubiquitous
insulation
Now Chinese researchers have come up with another tool in the energy-saving arsenal: a building material that can release and _____________ heat on demand, which makes a significant difference to the cost of heating and cooling buildings.