The correct answer is A. Crossing the street.
Step-by-step explanation
Being an observer refers to observing or looking at every detail of the surrounding environment or situation. This implies when you are an observer you understand a situation by noticing and understanding every detail. In this task, individuals mainly use their sense of sight, which allows individuals to understand visually elements, although observing often involves other senses such as hearing. This is necessary in the cases we need to remember information, perform precise actions, among others.
According to this, it is necessary to be an observer when crossing a street because this task or process requires concentration and precise actions and by observe you make sure that there is no danger of being hit by a car before crossing. So, the correct answer is A. Crossing the street