Explanation
Correct answer: B.
Choice B is the best answer. “In doing so” logically signals that the information in this sentence—that the medical students develop better observational skills—is an outcome of the action described in the previous sentence (the students learning art-based techniques).
Why the other choices are wrong
Choice A
Choice A is incorrect because “by contrast” illogically signals that the students developing better observational skills contrasts with the previous information about learning art-based techniques. Instead, the students’ improved skills are a direct result of learning those techniques.
Choice C
Choice C is incorrect because “for example” illogically signals that the students developing better observational skills is a specific example of learning art-based techniques. Instead, the students’ improved skills are a direct result of learning those techniques.
Choice D
Choice D is incorrect because “nevertheless” illogically signals that the students develop better observational skills despite the previous information about learning art-based techniques. Instead, the students’ improved skills are a direct result of learning those techniques.