Question

The U.S. and Australia have refused to sign the Kyoto Protocol _____.

because the agreement was drafted in secret
in protest of Communist member states like Cuba
because the Protocol challenges the UN
because they think it will have a negative effect on their economies

Answer 1

The answer to the question is the last item.

The United States and Australia have refused to sign the Kyoto Protocol "because they think it will have a negative effect on their economy". Yes, it is a popular belief that it will cause a bad effect on the economic status.