Answer:
B. I hope you like watching baseball, I really love it.
Step-by-step explanation:
A run-on sentence is a sentence consisting of two or more independent clauses (groups of words expressing a complete thought) not joined with a period, semicolon or conjunction, but that instead are connected improperly with a comma or no punctuation at all.
Sentence B is an example of this type of sentence error because both independent clauses (I hope you like watching baseball and I really love it) are incorrectly joined with a comma when they should be separated by a period or a semicolon.