Descriptive writing is a form of formal composition. You should pay attention to the form of your writing and avoid fragments and run-on sentences.
Here's my sample answer to the question:
Reading books is one of the best hobbies one can possess. A book acts as company during loneliness, for it takes its readers to an imaginary world. It may help, on another hand, to enhance knowledge about different disciplines and enlighten our minds as we explore new thoughts and information.