The author wouldn’t agree with (A), because one of the author’s points is that cuts to domestic spending, which some contend are a result of increased international debt (borrowing), might actually help the environment by stopping implementation of harmful programs.

There’s no support for the author’s agreement. The author does acknowledge that cuts to domestic spending might lead to cuts in subsidies for practices that reduce pollution. Whether those subsidies are effective in reducing pollution is not something the author takes a position on.

(C) mixes up the exports promotions hypothesis and the argument about cuts to domestic spending. Those are two different arguments presented by environmentalists for why increased international debt would lead to decreased quality of life. But the environmentalists never say that encouraging production of exports leads to decreased domestic spending. What they say is that increased international debt leads to both more exports and cuts to domestic spending.

In any case, this question asks us about the author’s perspective, not the environmentalists’. And the author never says that encouraging the production of exports leads to decreased domestic spending. The author never actually agrees that production of exports leads to anything – part of the author’s point is that there’s not enough evidence to tell us the results of increased exports.

(D) states a requirement in order for international debt payments to be a problem. But, the author never suggests any requirement for international debt payments being a problem. The author only calls into question the sufficiency of the environmentalists’ evidence.

Supported. Here, the author indicates that cutting domestic spending (“fiscal discipline or economic restructuring”) can benefit a country by stopping harmful spending. It’s reasonable to think that stopping something harmful is a beneficial thing to do.