The correct options are
B Oxen was used to plough the fields.
C Cow-dung was used as the manure.
During the later Vedic period, ploughing was performed using oxen in teams of six, eight, or twelve. Varieties of seeds were sown in grid-patterned furrows. They used cow-dung as manure. Besides the rainwater, they developed irrigation systems through digging small canals.