In the united states there are many jobs that require a person to be bilingual. which second language is most useful for employment

Depends on the profession. For most, Spanish would be the most useful due to the increased amount of Spanish native speakers in the USA. But in girls of science or technology, possibly more Asian languages would help since East Asia is a big producer in those fields.

Depends on what profession you want to pursue, the second most spoken language in the united states of america is Spanish and with professions like tourism you will most definitely need to learn that one along with others, but Chinese is the most used language in the world(Mostly due to the giant population of china.), so if your working just inside the united states definitely Spanish, but if your dealing with something like foreign trade you might want to learn Chinese.

The correct answer is a.