Correct Option (D)
The original statement, "We shall go either for a picnic or for trekking," asserts that at least one of these two activities will take place. To falsify this claim, a scenario must occur where neither activity happens. Option (D), "We do not go either for picnic or for trekking," directly negates the original statement by indicating that neither the picnic nor the trekking activity will be undertaken. This condition makes the initial claim demonstrably false.
Incorrect Options:
- Option (A): "We go for a picnic but not for trekking." If this is true, the original statement ("either for a picnic or for trekking") remains true because the condition of going for a picnic is met. Therefore, this scenario does not falsify the claim.
- Option (B): "Activities such as picnic and trekking are encouraged by the health authorities." This statement provides external information about the general encouragement of these activities. It is irrelevant to whether the specific claim about "we" going for a picnic or trekking is true or false.
- Option (C): "We go for trekking and not for picnic." Similar to option (A), if this is true, the original statement ("either for a picnic or for trekking") remains true because the condition of going for trekking is met. Thus, this scenario does not falsify the claim.