Explanation
Correct answer: B.
Choice B is the best answer. The convention being tested is the use and punctuation of a relative clause. This choice correctly uses the relative pronoun “that” and no punctuation to create an integrated relative clause that provides essential information about the noun phrase (“graffiti-like scribbles”) that it modifies.
Why the other choices are wrong
Choice A
Choice A is incorrect because no punctuation is needed between the integrated relative clause beginning with “that often” and the noun phrase that it modifies (“graffiti-like scribbles”).
Choice C
Choice C is incorrect because no punctuation is needed between the integrated relative clause beginning with “that often” and the noun phrase that it modifies (“graffiti-like scribbles”).
Choice D
Choice D is incorrect because no punctuation is needed between the integrated relative clause beginning with “that often” and the noun phrase that it modifies (“graffiti-like scribbles”).