The correct option is A
Only improved varieties of crop
Basically, germplasm is genetic material of the germ cells. Any living tissue from which new plants can be grown, is included under germplasm which may be a seed, leaves, pollen etc.
Germplasm is meant for the conservation of living genetic resources for plant breeding. Hence, only improved and superior varieties of crops are included.
So, the correct answer is 'Only improved varieties of crop'.