题目

The oldest and most common source(来源) of renewable energy known to man, biomass is one of the most important forms energy production in the United States and elsewhere. Since such a wide variety of biomass materials is everywhere ---- from trees and grasses to agricultural and city ---- life wastes ----biomass promises to play a continuing role in providing power and heat for millions of people around the world. According to the Union of Concerned Scientists(UCS), biomass is a kind of renewable energy source that produces no carbon dioxide(二氧化碳), because the energy it contThe journey around the world took the old sailor nine months, _____ the sailing time was 226 days. [     ]A. of which B. during which C. from which D. for which