Read the paragraph. [1] People living in the northeast United States enjoy having four distinct seasons, they are sometimes disappointed, though, at how these seasons develop. [2] Their disappointment shows when characteristics of the previous season last far into the current one. [3] For example, occasionally the winter weather will continue until late May, and summer weather sometimes lasts through late October. [4] When this happens, Northeasterners will complain, "We didn't have a real spring (or fall) this year." Which sentence in the paragraph is a run-on?

a
Sentence 1
b
Sentence 2
c
Sentence 3
d
Sentence 4