What should come in place of '?' in the given series?

An indifference curve is: 

Which branch of agriculture deals with principles and practices of soil, water and crop management?

Which among the following is a green house gas?

Among the following, which represents a true example of a biological control strategy used specifically against insect pests?

How much is the gestation Period of Swine?

Which soil texture class is best for agriculture due to balanced properties?

In mango cultivation, what physiological disorder is effectively controlled by applying paclobutrazol to the soil?

What does the gravimetric method measure in relation to soil moisture?

Reproductive phase of rice begins with

Given below are two statements:

Statement I: Salinity present in the irrigation water is given in terms of ESR value.