Concept:Choose the word that fits the action of improving an old building.
Explanation:The sentence talks about "dilapidated" classroom blocks, meaning they are old and in poor condition.
"Renovate" means to restore something old, especially a building, to a good condition.
"Erect" means to build something new, not restore an existing building.
"Patch" means to repair a small part, not the whole building.
"Fabricate" means to make or invent something, which does not suit this context.
Answer:B. renovate