(i) to achieve stabilisation in Greenhouse gas concentration: This is the primary objective of the Kyoto Protocol. It aimed to reduce greenhouse gas (GHG) emissions from developed countries to combat global warming. This is correct.
(ii) to control persistent organic pollutants: This is the objective of the Stockholm Convention, not the Kyoto Protocol. So, this is incorrect.
(iii) to reduce ozone depletion: This is the objective of the Montreal Protocol, not the Kyoto Protocol. So, this is incorrect.
(iv) to ensure that food production is not threatened: This is an underlying goal of climate change mitigation efforts, including the Kyoto Protocol. Stabilizing GHG concentrations aims to prevent severe climate impacts that could threaten food security. While not a direct mechanism, it's a fundamental objective linked to climate action. This is correct.
Therefore, (i) and (iv) are the major objectives.