Every five years, the government tries to tell Americans what to put in their bellies. Eat more vegetables. Dial back the fats. It’s all based on the best available science for leading a healthy life. But the best available science also has a lot to say about what those food choices do to the environment, and some researchers are annoyed that new dietary recommendations of the USDA (United States Department of Agriculture) released yesterday seem to utterly ignore that fact.

        Broadly, the 2016-2020 dietary recommendations aim for balance: More vegetables, leaner meats and far less sugar.

        But Americans consume more calories per capita than almost any other country in the world. So the things Americans eat have a huge impact on climate change. Soil tilling releases carbon dioxide, and delivery vehicles emit exhaust. The government’s dietary guidelines could have done a lot to lower that climate cost. Not just because of their position of authority: The guidelines drive billions of dollars of food production through federal programs like school lunches and nutrition assistance for the needy.

        On its own, plant and animal agriculture contributes 9 percent of all the country’s greenhouse gas emissions. That’s not counting the fuel burned in transportation, processing, refrigeration, and other waypoints between farm and belly. Red meats are among the biggest and most notorious emitters, but trucking a salad from California to Minnesota in January also carries a significant burden. And greenhouse gas emissions aren’t the whole story. Food production is the largest user of fresh water, largest contributor to the loss of biodiversity, and a major contributor to using up natural resources.

        All of these points and more showed up in the Dietary Guidelines Advisory Committee’s scientific report, released last February. Miriam Nelson chaired the subcommittee in charge of sustainability for the report, and is disappointed that eating less meat and buying local food aren’t in the final product. “Especially if you consider that eating less meat, especially red and processed, has health benefits,” she says.

        So what happened? The official response is that sustainability falls too far outside the guidelines’ official scope, which is to provide “nutritional and dietary information.”

        Possibly the agencies in charge of drafting the decisions are too close to the industries they are supposed to regulate. On one hand, the USDA is compiling dietary advice. On the other, their clients are US agriculture companies.

        The line about keeping the guidelines’ scope to nutrition and diet doesn’t ring quite right with researchers. David Wallinga, for example, says “In previous guidelines, they’ve always been concerned with things like food security—which is presumably the mission of the USDA. You absolutely need to be worried about climate impacts and future sustainability if you want secure food in the future.”

解析：C。根据题干中的the neglect of sustainability可定位至原文倒数第三段第二句。该句说到，可持续性的问题已经远远超出了指南的官方范围——即提供“营养和饮食信息”。随后在下一段作者指出了原因：可能是负责起草决策的机构与他们理应监管的行业关系过于密切（too close）。一方面，美国农业部正在编写膳食建议。另一方面，他们的客户又是美国的农业公司（agriculture companies）。由此可知，在作者看来，膳食指南忽视了可持续性的问题是由于美国农业部和农业公司的关系过于密切，故正确答案为C。

错项排除：最后一段第二句提到，在以前的指南中，研究人员一直关注类似食品安全（food security）这样的问题——这想必是美国农业部的使命所在。但倒数第三段也提到，官方回应膳食建议的范围是提供“营养和饮食信息”。由此可知，膳食指南不仅会关注食品安全问题，也会提供营养和饮食信息方面的膳食建议，而且这也不是其忽视可持续性的原因所在，故A、B两项错误。D项利用原文倒数第二段第一句中出现的regulate进行干扰，但该句说的是负责起草决策的机构与他们理应监管的行业关系过于密切，并不是说它对该行业监管不到位，D项属于过度推断，故错误。