passage
Historically, the biggest challenge to world agriculture has been to achieve a balance between demand for and supply of food. At the level of individual countries, the demand-supply balance can be a critical issue for a closed economy, especially if it is a populous economy and its domestic agriculture is not growing sufficiently enough to ensure food supplies, on an enduring basis; it is not so much and not always, of a constraint for an open, and growing economy, which has adequate exchange surplues to buy food abroad. For the world as a whole, Spply-demand balance is always an inescapable prerequisite for warding *** hunger and starvation. However, global availability of adequate supply does not necessarily mean that food would automatically move from countries of surplus to counteries of deficit if the latter lack in purchasing power. The uneven distribution of Hunger, starvation, under or malnourishment, etc., at the world-level, thus owes itself to the presence of emptypock hungry mouths, overwhelmingly confined to the underdeveloped economies. Inasmuch as ‘a two-square meal’ is of elemental significance to basic human existence, the issue of worldwide supply$ of food has been gaining significance, in recent times, both because the quantum and the composition of demand has been undergoing big changes, and because, in recent years, the capabilities individual countries to generate uninterrupted chain of food supplies have come under strain. Food production, marketing and prices, especially price-affordability by the poor in the developing world, have become global issues that need global thinking and global solutions.
According to the above passage, the biggest challenge to world agriculture is:
(a) to find sufficient land for agriculture and to expand food processing industries
(b) to eradicate hunger in underdeveloped countries
(c) to achieve a balance between the production of food and non-food items
(d) to achieve a balance between demand for and supply of food
