Explanation
Correct answer: A.
Choice A is the best answer. The convention being tested is subject-modifier placement. This choice ensures that the introductory phrase “upon recovering two years later” appears immediately before the noun it modifies (“Henry”), clearly establishing that Henry recovered two years later.
Why the other choices are wrong
Choice B
Choice B is incorrect because it results in a dangling modifier. The placement of the noun phrase “the reign of Henry” immediately after the introductory phrase illogically suggests that the reign of Henry recovered two years later.
Choice C
Choice C is incorrect because it results in a dangling modifier. The placement of the noun phrase “Henry’s reign” immediately after the introductory phrase illogically suggests that Henry’s reign recovered two years later.
Choice D
Choice D is incorrect because it results in a dangling modifier. The placement of the function word “it” immediately after the introductory phrase illogically suggests that “it” recovered two years later.