Many business offices are located in buildings having 2-8 floors. If a…

The problem states that any building with more than 3 floors must have a lift. To determine which statement must be true, we analyze the options based on this rule.\nOption B is correct because a building with a 7th floor necessarily has at least 7 floors. Since 7 is greater than 3, the condition 'more than 3 floors' is satisfied. Therefore, such a building must have a lift, making the presence of lifts on 7th floors logically necessary.\nOption A is incorrect because buildings with exactly 2 or 3 floors are not required to have lifts, but the statement implies they definitely do not, which is an assumption. Option C is wrong because it claims only floors above the 3rd have lifts, ignoring that buildings with more than 3 floors might also have lifts on lower floors. Option D is too broad, as buildings with only 2 or 3 floors might not have lifts at all. Thus, Option B is the only statement that must be true based on the given premises.