Why does Sachar include the line "He didn't know he was Stanley's great-great-grandfather in this
flashback?
O It makes it clear that Stanley has never met or heard
of his great-great-grandfather.
It explains to the reader that Elya was indeed
Stanley's great-great-grandfather.
It is a funny way of pointing out that Stanley and
Elya are clearly not living at the same time.
It is a silly way of letting the reader know that Elya
and Stanley are not really related to each other.

It explains to the reader that Elya was indeed  Stanley's great-great-grandfather.

Explanation:

The story "Holes" by Louis Sachar tells the story of how a curse by a 'witch' led to the misfortune of the victim's family throughout his generations. Stanley Yelnats' grandfather Elya Yelnats did not keep his promise to the gypsy Madame Zeroni, which led to the unfortunate life of his great-great-grandson Stanley.

In chapter 7, the author includes the family history of Stanley and narrates how the 'misfortune' of being 'cursed' by the gypsy follows the Yelnats family. He included the line "He didn't know he was Stanley's great-great-grandfather" to make the point clear that Elya was indeed his great-great-grandfather who was a "no-good-dirty-rotten-pig-stealing-great-great-grandfather".

Thus, the correct answer is the second option.

a good summary is that there was a girl living in ny named nolan and was poor and the lack of waters proves here strenthghs in the times of hardships