A run-on sentence in the provided options is 'Learning to play a musical instrument is fun it also changes how the brain functions.'
Learning to play a musical instrument is fun it also changes how the brain functions. This sentence is a run-on sentence because it combines two independent clauses without appropriate punctuation or a conjunction to separate them. Run-on sentences can make the text confusing and affect its readability.
https://brainly.com/question/12121996