Answer: A) death arrived at her door like an unwelcome stray dog.
Explanation: A simile is a figure of speech that consists in making a comparison between elements that aren't obviously related, this comparison is made using the words "like" and "as." From the given options, the excerpt that represents an example of a simile, is the corresponding to option A, because it compares death to an unwelcome stray dog by using the word "like."
The correct answer is: The details about how Lexie will help the young man.
This blog post about the service that eight-month-old Lexie will provide the young blind man who's going to take her, informs the reader of the ways Lexie (and the other dogs in the organization she was trained in) can help in the daily life of a visually-impaired person.