In the following sentence, there is one or group of words underlined and one gap...

In this question, you are given a sentence with one word underlined and a gap to fill. You are to select the word that is most opposite in meaning to the underlined word and can also fill the gap in the sentence. The underlined word is "insane".

To understand what the question is asking, you need to know what the word "insane" means. "Insane" means having a mental illness or being mentally deranged. It is an antonym of "sane" which means being mentally healthy or having a sound mind.

In the sentence, it says "At certain times, some insane people appear to be as _____ as you or I." The word "appear" means to seem or look a certain way. So, the sentence is saying that sometimes, people who have a mental illness may seem just as normal as you or me.

Now, you need to select the word that is most opposite in meaning to "insane" and can also fill the gap in the sentence. The options are: normal, intelligent, sober, and sensitive.

The word that is most opposite in meaning to "insane" is "normal". The other options are not necessarily opposite in meaning to "insane". For example, being intelligent, sober, or sensitive does not necessarily mean that someone is not insane.

Therefore, the correct answer is Option A: normal.