D. Offensive
If a comment is culturally insensitive, it’s one that may be considered offensive to certain groups or cultures
Please add the rest of the question, so as I can answer it.
Answer: No change is needed
Explanation: This is because the first one would make it seem like you can either have sand or water when you need both. The second one contradicts earlier when it says that you need the sand making it seem you don't later on. The third one sounds like it is saying you either need all the materials or time when you need all of these things. So the last one is correct. This sentence already makes sense
Answer:
There are endless benefits to writing 20,000 words in a single day that you'll probably never discover until you do it.