Final answer:
The correct answer is (B) without, meaning that the task is accomplished continuously and without interruptions. In English, this preposition is used to connect ideas and imply the absence of something, in this case, frequent stops.
Step-by-step explanation:
The correct answer to the fill-in-the-blank question is (B) without. The complete sentence would be: Apparently, they manage to do so without making frequent stops. This indicates that whatever 'they' are managing to do is being accomplished without the need to stop frequently. The use of 'without' suggests a continuous action uninterrupted by stops, reflecting a skill or efficiency in the activity being described.
When constructing sentences in English, prepositions such as 'without' are often used to connect ideas or clauses. In this case, it implies the absence of interruptions which could hinder the task. Contextual clues, like words that signal contrast or concessions such as although, in spite of, or nevertheless, are often helpful in determining the correct use of such prepositions.