The answer is C because "for" is used both as a preposition and a conjunction.
Answer:
Small acts of kindness have big impact. Kindness is a really good thing for others—but also for your own wellbeing, according to science. It's also more prevalent than you might think, and a cause for optimism—even in pessimistic times. It found kindness positively contributes to all kinds of wellbeing.
D. The major islands are made up of one or more volcanoes, and volcanic activity continues there today.