What are the factors for which crop improvement is desirable?
i. Higher yield
ii. Improved quality
iii. Good appearance
iv. Disease resistance
v. More height
vi. Wider adaptability

The correct option is C i, ii, iv, vi
Crop improvement is done for following factors:
1. Higher yield: To increase the productivity of the crop per acre.
2. Improved Quality: quality is very important in order to overcome malnutrition. It varies from crop to crop.
3. Resistance to biotic and abiotic conditions: Biotic factors involve all kinds of pests whereas abiotic factors involve salinity, drough , water logging etc. Resistance to these stresses can improve crop production.
4. Maturity duration: crops maturing in less time are more desirable.
5. Wider adaptability: Crops should be able to survive in different climatic conditions.
6. Favourable agronomic characteristics: like more foliage for fodder plants.