Explanation
Correct answer: B.
Choice B is the best answer. "That said" logically signals that the statement in this sentence—that Metzinger offers a glimpse of four-dimensional space by depicting multiple, simultaneous perspectives—is true despite the point in the previous sentence (that Metzinger’s painting doesn’t technically represent a fourth dimension because humans can only see in three dimensions).
Why the other choices are wrong
Choice A
Choice A is incorrect because "moreover" illogically signals that the information in this sentence merely adds to the previous point about Metzinger’s painting. Instead, it provides information that is true despite that previous point.
Choice C
Choice C is incorrect because "in other words" illogically signals that the information in this sentence is a paraphrase or restatement of the previous point about Metzinger’s painting. Instead, it provides information that is true despite that previous point.
Choice D
Choice D is incorrect because "for example" illogically signals that the information in this sentence provides an example that supports the previous point about Metzinger’s painting. Instead, it provides information that is true despite that previous point.