If a farmer wishes to succeed, he must try to keep a wide gap between his consumption and his production. He must store a large quantity of grain (31) consuming all his grain immediately. He can continue to support himself and his family (32) he produces a surplus. He must use this surplus in three ways: as seed for sowing, as an insurance (33) the unpredictable effects of bad weather and as a commodity which he must sell in order to (34) old agricultural implements and obtain chemical fertilizers to (35) the soil. He may also need money to construct irrigation (36) and improve his farm in other ways. If no surplus is available, a farmer cannot be (37) . He must either sell some of his property or (38) extra fids in the form of loans. Naturally he will try to borrow money at a low (39) of interest, but loans of this kind are not (40) obtainable.

A. proportion
B. percentage
C. rate
D. ratio