Why must you be particularly careful here?

You chose both answer 1 and answer 2, which is correct. There are two main reasons to be extra cautious in this situation. First, fallen autumn leaves can make the road slippery, increasing the risk of skidding if you brake suddenly. Second, you must watch out for vehicles coming from the right, as in residential areas without traffic signs, the "right-before-left" rule applies, and cars from the right have priority. By understanding these risks, you'll be able to react safely in similar situations in the future.