Question

which is a run - on sentence? are these two lines parallel, or do they intersect? you must be going somewhere nice, your outfit is so elegant. sometimes feels nervous and uncomfortable when speaking in front of large groups.

Explanation:

A run - on sentence is a sentence in which two or more independent clauses (complete sentences) are joined without proper punctuation or conjunctions.

• The first option "Are these two lines parallel, or do they intersect?" is a compound sentence with a proper conjunction "or" and correct punctuation.
• The second option "You must be going somewhere nice, your outfit is so elegant." has two independent clauses ("You must be going somewhere nice" and "your outfit is so elegant") joined only by a comma, which is a run - on (comma splice).
• The third option "Sometimes feels nervous and uncomfortable when speaking in front of large groups." is a sentence fragment (missing a subject), not a run - on.

Answer:

You must be going somewhere nice, your outfit is so elegant.