I am using Android 4.0.4, and after not having downloaded anything pertaining to TTS, I am presented with two options when I go to use this functionality. There is the Google version, which is built into the OS, and there is the Samsung version. So, potentially, you have at least two options right out of the box, and at least one. As for the version, you shouldn't have a problem with that since TTS has been around for a few years now.
I was impressed with the Kindle Fire's text to speech ability that renders nearly any book as an audiobook.
Now I've been told that's more a function of Android's OS, and many apps with Android could do it. Since I'm tablet shopping, I gotta know.
What app or apps of Android's is responsible for the text to speech? What would I need to download?
What is the lowest version of Android that has this feature?

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