Concept:Corrugated means shaped into a series of parallel ridges and grooves so that the material becomes stronger and more rigid.
Explanation:In the sentence, "corrugated sheets" are roofing sheets that have been pressed or bent into a wavy, ridged form.
When a material is corrugated, it is folded into repeated ridges and hollow grooves running side by side.
This wavy pattern gives the sheet extra strength, which is why it is commonly used for roofing.
Among the options, "folded" is the nearest in meaning because corrugation involves bending a flat sheet into a series of folds.
"Iron" and "aluminium" simply name the materials that such sheets may be made from; they do not explain the meaning of the word "corrugated".
"Corrupted" means spoiled, damaged, or morally depraved, so it is completely unrelated to the idea of ridged roofing sheets.
Therefore, the word that best matches "corrugated" is "folded".
Answer:A. folded