Can you choose more than one option?
Because a conclusion should not repeat word-for-word the introducion (this would make it actually pretty redundant), but other than this, it should be all of the remaining! (but if i had to choose one, I'd go with "summarize the main points- this would be most effective and most relevant./)
So my answer is: it should restate the thesis AND summarize the main points AND be imaginative but it should NOT repeat the introduction word-for-word.