The correct options are
B Growing saplings and planting it in fields.
C Transplanting paddy involved back-breaking work.
There were major changes in agriculture during the Vedic age. This included the shift from use of wooden ploughshares to iron ploughshares. It also included transplantation of paddy where instead of scattering seeds on the ground and letting it sprout, saplings were grown and then planted in fields. This led to increase in production as more plants survived. However, this process involved back-breaking work which was performed by slave men and women.