Concept:The central office of an organisation is called "headquarters," not "headquarter."
Explanation:The sentence needs a word that means the main or central office of Asokoro.
"Headquarters" is a plural-form noun, but it can be used with a singular verb like "is located."
In this sentence, no possession is shown, so an apostrophe is not needed.
Options C and D contain apostrophes that suggest ownership, which is incorrect here.
Option A, "headquarter," is not the accepted singular form in standard English.
Therefore, the blank must be filled with the plain plural-form noun "headquarters."
Answer:B. headquarters