What is the primary goal of sustainable farming?

decreasing short-term costs and increasing long-term income

meeting current needs while preserving resources for the future

developing new crops to grow while still growing traditional varieties

testing and adopting new technologies for agriculture

Meeting current needs while preserving the resource for the future is the objective of sustainable farming.  

Explanation:

Sustainable farming uses methods that increase productivity but also understands that the precious natural resources are to be reserved for the future generations also.

Cultivating different types of crops to meet the needs of the population while using non renewable resources in limited amount is the method advocated by sustainable farming.  Nutrient replenishment has to be done adequately because once the land is depleted of its nutrients it becomes unsuitable for cultivation.

Over irrigation also produces negative effects by increasing the soil salinity. Productivity increase coupled with resource conservation is the aim of sustainable development.