Looking at the choices it appears that none of them equal to 1.7
1.7 means 1 whole and 7/10 of a whole, which is equivalent to 1 + 7/10
As a proper fraction it would look like this:
1 7/10
As an improper fraction it would look like this:
17/10
Since 17 and 10 share no common factors besides 1, the fraction in simplest form would be 17/10 (or if they're asking you for proper form: 1 7/10)