Some important music companies used laws to guard against______.A．illegal revising of tune

Some important music companies used laws to guard against______.

A．illegal revising of tunes by a girl over the Internet

B．illegal download of their music over the Internet

C．possible plagiarism over the Internet

D．downloading too many tunes with too less payment

请帮忙给出正确答案和分析，谢谢！