Se observa gente
de la oficina

a. de
b. por
c. alrededor

The correct answer is C. Alrededor

I'm not sure if you mean for us to translate or to answer. but i'll translate as these are questions for you to answer. 1. how long has it been since you've read a book? . 2. how long has it been since you've eaten breakfast? . 3. how long has it been since you've talked with your spanish professor?

B. por especies marinas d. por ningún tipo de especies