Concept:"Fortify" means to strengthen or make secure, especially against attack.
Explanation:In this sentence,
fortify means to make the building strong and safe against attack.
This is closest in meaning to making it
secure.
"Defend" means to fight against an attack, not necessarily to strengthen the building itself.
"Shield" means to protect by covering, while "support" means to hold something up.
None of those capture the exact idea of reinforcing the building.
Therefore, the correct option is B.
Answer:B. secure