Q. Archaeologists believe that the pieces of red – ware pottery excavated recently near Bhavnagar and __________________shed light on a hitherto dark 600-year period in the Harappan history of Gujarat.

1. estimated with a reasonable certainty as being about 3400 years old,
2. are estimated reasonably certain to be about 3400 years old,
3. estimated at about 3400 years old with reasonable certainty,
4. estimated with reasonable certainty to be about 3400 years old,