Based on the above passage, the following assumptions have been made:
1. Giant icebergs have a bearing on primary productivity and food chains of the Southern Ocean.
2. Melting of giant icebergs can produce climate change effects and impact world fisheries.

Which of the assumptions given above is/are valid?

Correct Option: (c) Both 1 and 2

The passage states that giant icebergs melt and release iron and other nutrients into the Southern Ocean, which supports high levels of phytoplankton growth. Since phytoplankton are the primary producers in marine ecosystems, they form the foundation of the ocean's food chains. Thus, Assumption 1 is valid. Furthermore, the passage notes that icebergs are responsible for storing up to 20 percent of carbon in the Southern Ocean by supporting phytoplankton growth. Therefore, the melting of giant icebergs directly impacts carbon storage, which has a bearing on climate change, and also influences the food web, which impacts world fisheries. Thus, Assumption 2 is also valid. Both assumptions are logically derived from the scientific relationships described in the text. Hence, the correct option is (c).