Which statement is true about the transitions because and as a result in the following sentences?

Amir reached his savings goal because he worked hard at his new job all summer. As a result, he was able to buy the new skates that he wanted.

(1 point)

Both because and as a result signal an effect.

Because signals an effect and as a result signals a cause.

Because signals a cause and as a result signals an effect.

Both because and as a result signal a cause.

Both because and as a result signal a cause.