Some tourist companies offer responsible ecotourism holidays to destinations across the world with one thing in common: All holidays contribute positively to the areas in which they work ... This means: Your holiday does good to the environment and people you visit, not harm. A better holiday doesn't cost you anymore. They offer good holidays that do good, not harm.6. The common goal of these tourist company destinations is ____________.A a good holiday that doesn't cost anythingB a good holiday that doesn't involve the local peopleC a good holiday that does no harm to the local environmentD a good holiday that does nothing to the local environment

根据提供的图片内容，我们需要解答第6题。

推导过程：

1. 阅读并理解原文：
   原文指出：“Some tourist companies offer responsible ecotourism holidays to destinations across the world with one thing in common: All holidays contribute positively to the areas in which they work ... This means: Your holiday does good to the environment and people you visit, not harm. A better holiday doesn't cost you anymore. They offer good holidays that do good, not harm.”
   这段话的核心意思是：这些旅游公司提供的生态旅游假期有一个共同点，那就是所有的假期都会对它们所在的地区产生积极的贡献（contribute positively）。具体来说，你的假期会对环境和当地人民有益（does good），而不是有害（not harm）。

2. 分析题目：
   题目问的是：“The common goal of these tourist company destinations is ________.”（这些旅游公司目的地的共同目标是________。）
   根据原文，这个共同目标是提供“do good, not harm”（有益无害）的假期。

3. 逐一分析选项：

   • A. a good holiday that doesn't cost anything (一个不花任何钱的假期)
     原文说的是“A better holiday doesn't cost you anymore”（更好的假期不会让你花费更多），意思是价格不会更高，而不是说完全免费（doesn't cost anything）。因此A错误。
   • B. a good holiday that doesn't involve the local people (一个不涉及当地人的假期)
     原文明确提到假期要对“people you visit”（你访问的人们）有益（does good），这意味着假期是与当地人相关的。因此B错误。
   • C. a good holiday that does no harm to the local environment (一个对当地环境无害的假期)
     原文强调假期要“do good to the environment... not harm”（对环境有益……而不是有害）。“does no harm”（无害）与原文中的“not harm”相符，并且是这种负责任旅游的基本目标。
   • D. a good holiday that does nothing to the local environment (一个对当地环境毫无影响的假期)
     原文说的是假期要对环境“do good”（有益），而“does nothing”（毫无影响）意味着既不产生积极影响也不产生消极影响，这与原文强调的“contribute positively”（积极贡献）不符。因此D错误。

4. 得出结论：
   综合比较，选项C最准确地概括了原文中提到的这些旅游公司目的地的共同目标，即提供对当地环境无害（且有益）的假期。

答案：
C