▶️ Answer/Explanation
To determine how many statements are supported, we must look only at the provided graph:
1. The graph only shows $CO_{2}$ and methane; it does not prove they were the only gases produced.
2. The data ends at $2015$, so it cannot support a claim about the “present day” (e.g., $2026$).
3. The graph shows emission quantity, not the potency or effect on climate change.
4. Looking at the bars, the methane bars are significantly shorter than the carbon dioxide bars for every year shown ($1990–2015$).
Therefore, only the final statement is supported by the visual data provided.
✅ Answer: (A)
1. The graph only shows $CO_{2}$ and methane; it does not prove they were the only gases produced.
2. The data ends at $2015$, so it cannot support a claim about the “present day” (e.g., $2026$).
3. The graph shows emission quantity, not the potency or effect on climate change.
4. Looking at the bars, the methane bars are significantly shorter than the carbon dioxide bars for every year shown ($1990–2015$).
Therefore, only the final statement is supported by the visual data provided.
✅ Answer: (A)
▶️ Answer/Explanation
When fertiliser enters a river, it causes an immediate increase in nutrient levels, leading to rapid growth of algae and subsequent death of plants. Bacteria then decompose this organic matter, and their population increases significantly. Because these bacteria are aerobic, they consume large amounts of dissolved oxygen for respiration, causing oxygen levels to plummet.
Looking at the graph, the point where the bacteria curve starts its sharp ascent and the oxygen curve begins its steep decline is at position A. At positions $B$ and $C$, the impact is already in progress or at its peak, while $D$ shows the recovery phase. Therefore, the point of entry must be the earliest point where these changes are triggered.
✅ Answer: (A)
▶️ Answer/Explanation
Eutrophication is the process where a body of water becomes overly enriched with minerals and nutrients, primarily nitrates and phosphates. Sewage contains high levels of these organic nutrients and detergents, which act as a fertilizer for aquatic plants. When sewage enters a lake or river, it triggers an “algal bloom,” where algae grow rapidly on the surface. This thick layer of algae blocks sunlight from reaching deeper plants, causing them to die. As bacteria decompose the dead organic matter, they consume the dissolved oxygen in the water, leading to the death of fish and other aerobic organisms. While carbon dioxide and methane are greenhouse gases and plastic is a physical pollutant, only sewage provides the nutrient load necessary for this biological collapse.
✅ Answer: (D)
✅ Answer: (D)