Correct Answer: Sedulous

Solution : The correct choice is the fourth option.

The word that means the same as "conscientious" is "sedulous."

The term "conscientious" refers to being diligent, careful, and thorough in one's work or duties. Similarly, "sedulous" implies diligence and dedication in carrying out tasks, making it a synonym for "conscientious."

The meanings of the other options are as follows:

Savage: Fierce, brutal, or untamed; it does not share the same meaning as "conscientious."

Casual: Relaxed, informal, or not serious; it contrasts with the careful and diligent nature of "conscientious."

Carefree: Without worries or responsibilities; it is an antonym of "conscientious."

Therefore, the correct synonym is sedulous.