Final answer:
All of the statements about passing other vehicles are true: it is dangerous to pass on two-lane roads, you should only pull out to pass if you have enough space, and you should always signal before passing.
Step-by-step explanation:
All of the statements given in options a, b, and c are true when it comes to passing other vehicles. All of the statements about passing other vehicles are true: it is dangerous to pass on two-lane roads, you should only pull out to pass if you have enough space, and you should always signal before passing.
Option a states that it is dangerous to pass on two-lane roads, which is correct because there is limited visibility and space. Option b indicates that you should only pull out to pass if you know you will have enough space to safely pull back into your lane, which is important to avoid collisions.
Option c emphasizes the importance of signaling before passing to alert other drivers of your intention. Therefore, option d - All of the above - is the correct answer as all the statements are true.