A potter choosing which type of clay to use for a piece considers two key factors:

Choice D is the best answer. The previous sentence tells us that potters think about the look and use of a piece when selecting clay. This sentence provides a specific example of a type of clay selected for its appearance, so the transition "for example" fits perfectly.

Choice A is incorrect. This choice uses a transition that indies a restatement of the same idea. But this sentence does more than just restate the previous idea. Instead, it provides a more specific example of the idea presented in the first sentence. Choice B is incorrect. This choice uses a disagreement transition. But this sentence actually agrees with the previous sentence. Both sentences suggest that desired look plays a role in the selection of clay types for pottery pieces. Choice C is incorrect. This choice uses a concluding transition. But this sentence doesn’t sum up the previous sentence. Instead, it gives a specific example of the idea presented in the previous sentence.