Usually, in a conclusion, you wrap up what you have been writing about the whole time. So, a conclusion is basically a summary of the whole text. You can introduce new ideas for the reader, but it is usually inadvisable. In a couple of sentences, you should finish your text, referring to the previous paragraphs and just wrap it all up nicely.
a. Oral Sex - this still causes transfer of sexual fluids which can spread HIV. Technically if sexual fluids come in contact with toilet seats or clothing (underwear, etc), than HIV can be spread through those. But the chances of contracting HIV must be slim for those options since the fluids need to find a cut or an open blood vessel to enter.
