When you are passing or being passed , remember to plan a( in case you need to avoid a collision . a . emergency maneuver. b . escape route . c. destination .d . way to get home

the answer is definitely c.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.