The correct answer is paradox.
Paradox is a figure of speech that combines two completely opposite things into one. In the excerpt above, we can see that the speaker is willing to wait for his/her loved one his/her entire life, however, only if they don't take too long to get to him/her. This is a paradox because they weren't willing to wait for them long in the first place, as it turns out.
Answer:
What are the most effective dog-training techniques? - a blog from an expert dog trainer
Why are dogs especially intelligent animals? - the encyclopedia entry "Canine"
How do scientists measure the intelligence of dogs? - an article from the Journal of Animal Biology
Explanation:
1. Dog-training : dog trainer!
2. Encyclopedias often give reasons on <em>why</em> and what more than anything.
3. Science journals give their methods and reasoning on their projects a lot.
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