Which one of the following is an improved variety of maize?

Four inbred lines of maize are crossed. This type of cross is known as:

Which widely grown variety of rice,developed by the International Rice Research Institute $(IRRI)$ in Manila,Philippines,helped solve the food crisis in Asia?

Which organization is involved in the production of hybrid varieties of maize?

The $....X....$ variety of Brassica is resistant to $.....Y.....$ disease.

Fill in the blanks in the following statements ($A$ to $C$):
$(A)$ The capacity to generate a whole plant from any cell/explant is called ......$(i)$ .......
$(B)$ The transfer of resistance genes occurs through ........$(ii)$ ........ . Subsequently,......$(iii)$ ....... occurs between the target and the source plant.
$(C)$ The rice variety $IR8$ was developed in the country ........$(iv)$ .