Match the terms of column-I with its meaning in the column-II and select the correct option.
Column-IColumn-IIa. Standing crop(i) Rate of production of organic matter during potosynthesisb. GPP(ii) Amount of nutrients present in a given timec. Secondary productivity(iii) Rate of formation of new organic matter by consumersd. Standing state(iv) Mass of living material at a particular time in a tropic level