Explanation: Each answer choice, with the exception of (D), the tributary system (a Chinese system consisting of independent countries acknowledging the supremacy of the Chinese emperor), is an agricultural innovation that boosted production. The chinampas, (A), were fields built on shallow lakes in Mesoamerica. The three-field system, (B), innovated crop rotation in medieval Europe. And the horse collar, (C), was used in many societies through history so that horses would be able to pull ploughs. Therefore, (D) is the answer.