Temperatures have risen nearly five times as rapidly on the Western Antarctic Peninsula than the global average over the past five decades. Researchers have now found that melting glaciers are causing a loss of species diversity among benthos in the coastal waters off the Antarctic Peninsula, impacting an entire seafloor ecosystem. They believe increased levels of suspended sediment in water to be the cause of the dwindling biodiversity in the coastal region.

On the basis of the above passage, the following assumptions have been made:
1. Regions of glaciers warm faster than other regions due to global warming.
2. Global warming can lead to seafloor sedimentation in some areas.
3. Melting glaciers can reduce marine biodiversity in some areas.
Which of the above assumptions is/are valid?

The correct option is 2 and 3 only.

To understand why this is the correct choice, let us analyze the passage and evaluate each assumption systematically:

Evaluating Assumption 1: "Regions of glaciers warm faster than other regions due to global warming."
The passage mentions that temperatures have risen nearly five times as rapidly on the Western Antarctic Peninsula compared to the global average. However, this is a localized observation about a specific region (the Western Antarctic Peninsula). We cannot generalize this specific fact to assume that all glacial regions globally warm faster than non-glacial regions. Therefore, Assumption 1 is not valid.

Evaluating Assumption 2: "Global warming can lead to seafloor sedimentation in some areas."
According to the passage, rising temperatures (global warming) lead to melting glaciers, which researchers believe cause "increased levels of suspended sediment in water" off the Antarctic Peninsula, impacting the seafloor ecosystem. Because global warming triggers the melting that increases water sediment, it is logical to assume that global warming can lead to seafloor sedimentation in some areas. Therefore, Assumption 2 is valid.

Evaluating Assumption 3: "Melting glaciers can reduce marine biodiversity in some areas."
The passage explicitly states that "melting glaciers are causing a loss of species diversity among benthos in the coastal waters off the Antarctic Peninsula." Benthos are organisms that live on, in, or near the seafloor, which means a loss in their diversity is a direct reduction in marine biodiversity. Thus, Assumption 3 is directly supported by the text and is valid.

Since only assumptions 2 and 3 are logically supported by the passage, the correct option is 2 and 3 only.