B, C - Incorrect: The plural pronoun their does not agree with the singular noun the organization
D, E - Incorrect: The adverb of degree only is incorrectly placed; it incorrectly modifies the hospitalization instead of medical costs. This option also creates a misplaced modifier because it illogically implies that the medical costs decided on their health care policy.
Choice E confuses the meaning further by using the singular verb was with the plural subject costs.
A - Correct: This option correctly uses the singular pronoun its for the singular noun the organization
A is the correct answer.