Answer: Effortless.
Explanation: You know suffixes right? They are the end part of a word such as -ness, -ment, and -ism. Negative suffixes are pretty much the same thing, but they're words with the suffix -less in them. Examples of negative suffixes are hopeless, fearless, homeless, and tasteless. Effortless has -less in it, so therefore, it's a negative suffix.
Let me know if it's right! :)
