Hello. You did not inform the excerpt to which this question refers, which makes it impossible for it to be answered accurately. However, I will try to help you in the best possible way.
It is only possible to answer this question after reading the excerpt. However, it is important to inform that the theme of a text is the subject to which that text addresses, which is directly connected with the message that the text intends to present. Thus, when reading the excerpt you must understand what subject is being addressed, to be able to find the theme. You can find this subject by thinking about what the excerpt is referring to, what meaning it is trying to address, what lesson the excerpt teaches and how that excerpt can fit into real society.
The answer is a <span>situation that seems to be contradictory but actually, presents a truth. It seems unreal because it gives a different light of understanding a subject. A paradox has a possibility to happen although it looks impossible or contradicting.</span>
Is after the underlined word? If so, it'd be a preposition. It's followed by a noun.
The answer is B because "I have visited many cities including the following" indicates that there is going to be a list of cities. A colon is used to introduce a series of items or to separate two independent clauses; however the second sentence has to add on to the first.
