Respuesta :
Answer:
C.The first structures using steel were built.
Explanation:
The use of steel to build buildings began at the beginning of the 20th century, but became widespread after the Second World War, when this material became more available. Steel buildings have been widely accepted because they can develop structures much higher than with concrete, a situation highly valued in the large cities of the world where land is scarce. The development of steel buildings has had great innovation with the use of computers.