Why are you not allowed to take the turn now?

Your answer is correct because the yellow car is in a lane that requires turning; it cannot go straight. According to German traffic rules, lane markings and arrows on the road indicate the allowed directions for each lane, especially before intersections. If a lane has a mandatory turn arrow, like left only, you must follow that direction and are not allowed to continue straight. This ensures traffic flows safely and predictably. Ignoring these lane markings can cause confusion and accidents. The color or type of the vehicle is not relevant—what matters is the lane indication. So, the yellow car cannot go straight because it is in a lane designated for turning only.