Okay. So this one asks: Crossing over involves each of the following except what? Let's run through them and see what we have.
Option A reads the transfer of DNA between two non-sister chromatids and that definitely happens during crossing over. That is, like, the key event of crossing over; when we get the genetic swap or that kind of DNA exchange between two non-sister chromatids. We're going to cross out A because that definitely does happen.
Option B reads the transfer of DNA between two sister chromatids. Now, that doesn't really need to happen because sister chromatids are identical, so they don't need to be transferring DNA to each other; it's going to be the exact same DNA. So, B is looking pretty promising; let's circle B.
Option C reads the alignment of homologous chromosomes, and again, that is a key feature of crossing over that will kind of set the stage for that genetic swap to be taking place. So, C does happen.
Option D reads all of the above, which we know is not true because B does not take place. So our answer here is B: crossing over involves each of the following except the transfer of DNA between sister chromatids. There you go.