Indicate the diagrams you would consider most appropriate to represent the following statistical data, stating briefly the reasons for your choice: (i) Marks scored by two selected candidates in each of six subjects tested at an examination; (ii) Total value of Indian exports and imports during the years 19561972; (iii) Middleclass cost of living index numbers in Bombay and Calcutta during the years 19611972; (iv) Distribution of civil conditions of persons enumerated in 1971-census.