(a) State the law of diminishing returns in agricultural production. (2 marks)

(b) The table below shows the relationship between quantities of fertilizers used and the corresponding yields of sorghum.

Quantity of fertilizer (Bags)	Sorghum yield (kg)
0	8
6	30
12	50
18	90
24	140
28	170
32	190
36	200
40	200
46	190

(i) Use the table to draw an input-output graph (3 marks) 
(ii) Explain the relationships between fertilizer input and sorghum yield. (2 marks)

 (c) Enumerate four functions of an agricultural extension agent. (4 marks)

(d) State five benefits of commodity boards in the marketing of agricultural produce in West Africa. (5 marks)