Hich choice best revises sentence 6? When salmon are hatched, this takes place upstream before they travel downstream to the ocean where they spend most of their lives.

Salmon are hatched upstream where the river is shallow and gravelly, then they swim downstream to the ocean, and live there most of their lives.

After being hatched in the shallow, gravelly area of a river, salmon swim downstream to the ocean where they spend most of their lives.

When salmon are first hatched, in a shallow gravelly area of a river, they then swim downstream to the ocean for the rest of their lives.