---Can you come to my party on Saturday afternoon?

---       .I’ll have to help my parents.

A．Sorry, I can’t.

B．Yes, I’d love to.

C．Let’s go.

D．No, I don’t think so.

Chemical pollution will bring about a threat to agriculture and food chain, and ________ to human health.[      ]

A. frequently

B. significantly

C. steadily

D. consequently