Question

one of the reasons why many young people _______ a computer with ease is because they were born in the digital technology era (use)

Answer 1

One of the reasons why many young people USE a computer with (...)

Lembre-se que verbos no presente só recebem um s no final quando é He, She ou It. Na frase, é they, logo, vamos usar USE.

Se a frase fosse:

One of the reasons why Luiza ___a computer (...), você usaria USES

Ficando, ''One of the reasons why Luiza USES a computer (...)
 
Espero ter ajudado!