The correct option is D Standing crop
The measure of the total biomass of an ecosystem or any of its components at a given time is called standing crop biomas. It is the total weight of the organisms which are present in a particular location at a particular time. It is usually expressed as grams of organic matter per square meter (g/m2) .The total amount of inorganic substances i.e. minerals such as phosphorous, sulfur, nitrogen, hydrogen, etc. present at any given time in the environment of an ecosystem is known as standing state.