With reference to the above passage, the following assumptions have been made: 1. Global warming is causing spring to come early and for longer durations. 2. Early spring and longer period of spring is not good for bird populations. Which of the above assumptions is/are correct?

1. A. 1 only
2. B. 2 only
3. C. Both 1 and 2
4. D. Neither 1 nor 2

Answer: D

Explanation

Assumption 1: The passage states that ‘warmer winters with less snow resulted in a longer lag time between spring events and a more protracted vernal window.’ While this describes a change in spring timing, the passage does not explicitly attribute this phenomenon to ‘global warming’. It presents an observation without stating its cause. Therefore, assuming global warming is the cause goes beyond the information provided.
Assumption 2: The passage mentions, ‘As the ice melts earlier, the birds don’t return, causing a delay, or lengthening in springtime ecological events.’ This indicates a disruption in bird migration patterns. However, the passage does not explicitly state that this disruption is ‘not good’ for bird populations. It merely describes a change in ecological events without assigning a positive or negative value to it. Therefore, this assumption is also not directly supported by the passage. Since neither assumption can be definitively concluded from the passage, neither is correct.