题目选项分析

Macrophages are cells that play a role in the response of the immune system of mice and other mammals to invasive organisms such as bacteria. Unlike other mice, mice that are genetically incapable of making these particular cells do not show elevated levels of nitrates when infected with bacteria.

The statements above, if true, provide the most support for which of the following conclusions?

【选项】Injections of nitrates into mice that lack macrophages will not enhance the ability of these animals' immune systems to fight off infection.