The traditional knowledge should be used through :

Concept: A stated-detail comprehension question is settled by traceability, not by plausibility. The passage's own wording fixes the answer, so the option that must be chosen is the one that restates an assertion the author has actually made about the point in question; an idea that merely sounds reasonable about the subject, or that the passage raises in some other role, does not satisfy that test.

Application: The stem asks by what route traditional knowledge is to be used. The passage settles the point in one sentence: “Local coping strategies and knowledge need to be used in synergy with government and local interventions.” The route the author prescribes is therefore a synergy — local coping strategies and knowledge on one side, government and local interventions on the other, working as one rather than separately. Read that relation precisely: the passage does not merely ask government and local interventions to agree among themselves, it asks that local knowledge be put to work in synergy with them. The offered route built on that synergy of government and local interventions is the one the author names; the remaining three routes are never put forward by the author as the way traditional knowledge is to be used.

Cross-check — what the passage does say about the other ideas offered:

• Dissemination: the passage describes traditional knowledge as accumulated within local communities through experience of past weather patterns, but it nowhere prescribes circulating that knowledge outward as the way to use it.

• Improvement in national circumstances: national circumstances appear only in “The need of adaptation interventions depends on national circumstances” — they govern how much intervention is required, not how traditional knowledge is applied.

• Modern technology: technology appears as an adaptation measure of its own (“technological options such as increased sea defences or flood-proof houses on stilts”), and communities are told to adopt “appropriate technologies” while making the most of traditional knowledge — the two are placed side by side, so technology is not presented as the channel for traditional knowledge.

Result: on the author’s own wording, traditional knowledge is to be used through synergy with government and local interventions — the route the offered option phrases as synergy between government and local interventions.