What became known as the gold of north america?

i beleive its 1)aids

seeing as no choices were provided, i'll do my best to answer it from knowledge.

job specialization promotes work ethic to the person doing the job. he/she may be strong in the arms and able to lift things, specializing him/her in a job where you lift and carry.

i dont no the claim so it's hard to answer but i think he would go to the people to decide. : ) ; )