Question

The Boston terrier breed of dogs has an interesting history that begins, of course, in Boston. It is believed that Boston terriers can be traced back to a dog named “Judge” who was sold to a man living in Boston named Hooper in 1870. Hooper’s “Judge” was the first dog to have all the characteristics of the Boston terrier. Appropriately, he is considered the ancestor of almost all true modern Boston terriers.
Which sentence from the passage contains a supporting detail that answers the question, When did this take place?

It is believed that Boston terriers can be traced back to a dog named “Judge” who was sold to a man living in Boston named Hooper in 1870.

Appropriately, he is considered the ancestor of almost all true modern Boston terriers.

Hooper’s “Judge” was the first dog to have all the characteristics of the Boston terrier.

The Boston terrier breed of dogs has an interesting history that begins, of course, in Boston.

Answer 1

Answer:

It is believed that Boston terriers can be traced back to a dog named “Judge” who was sold to a man living in Boston named Hooper in 1870.

Explanation:

Answer 2

Since the questions asks about when, you would expect that the supporting detail would contain a time or date. That sentence would be: 

It is believed that Boston terriers can be traced back to a dog named “Judge” who was sold to a man living in Boston named Hooper in 1870.

Therefore, it happened in year 1870.