Why is there a need for varietal improvement?

Find out the correct sentence:
$(i)$ Hybridisation means crossing between genetically dissimilar plants.
$(ii)$ Cross between two varieties is called as interspecific hybridisation.
$(iii)$ Introducing genes of desired character into a plant gives genetically modified crop.
$(iv)$ Cross between plants of two species is called as inter-varietal hybridisation.

Simran and Ria were enjoying dancing in the rain. Suddenly, a question struck Ria's mind: "How does rain fall on Earth?" To this, her elder sister Simran explained the water cycle: how clouds are formed when water evaporates due to the heating of water bodies, rises, expands, and cools to form tiny droplets that grow larger to form clouds, which then sprinkle rainwater onto the Earth. Simran also told Ria that this rainwater is essential and precious and must be conserved.
$(a)$ Which values are displayed by Simran?
$(b)$ Why is water conservation necessary?

Once Ravi and Aman were cooking rice in the kitchen and accidentally Aman's hand got a severe burn while opening the lid of the cooking vessel. Immediately,Ravi applied ice on his hand,then applied an ointment,and told him to cook carefully as he had been hurt by steam,and steam causes more severe burns. Aman thanked Ravi and smiled.
$(a)$ According to you,what kind of qualities are shown by Ravi?
$(b)$ How does steam produce more severe burns than boiling water?

How do Sunhemp or guar help in crop production management? How is it better than fertilizers?

The preventive and control measures which are used before grains are stored for future use include: