题目选项分析

In laboratory rats, a low dose of aspirin usually suffices to block production of thromboxane, a substance that promotes blood clotting, but does not seriously interfere with the production of prostacyclin, which prevents clotting.

In laboratory rats, a low dose of aspirin usually suffices to block production of thromboxane, which is a substance to promote blood clotting, but does not seriously interfere with the production of prostacyclin, which prevents clotting.