other + N plural: other … another + N singular: (add) 1 more
every + N singular: each… one + N singular: one…
After the blank is “people” => use “other”
…texting can signal your unavailability to (28) other people in the same way that wearing sunglasses and headphones does.
=> Texting can signal your absence to others in the same way that wearing sunglasses and headphones does.