Correct option is B
The correct substitution of the highlighted words is (b) construction of the ground floor.
Explanation: The word "flour" is incorrectly used here. The sentence refers to the completion of building a part of a building, and the correct term for the lowest level is "floor", not "flour," which is a powder used in baking.
Example: They completed the construction of the ground floor last week.
Information Booster:
· “Flour” and “floor” are homophones (sound alike but have different meanings and spellings).
· Confusing them is a common lexical error in writing.