The correct answer is A. sparingly.
To use something sparingly is to use it in a careful and economical way. This means using only
as much as is needed and not wasting any. In the context of the question, the country’s resources should be used in a way that does not deplete them or cause them to be used up too quickly.The other options are not as accurate. Option B. reasonably means using something in a way that is fair and just. This does not necessarily mean using it sparingly. Option C. adequately means using something in a way that is sufficient or enough. This does not necessarily mean using it sparingly either. Option D. immensely means using something in a very large or great amount. This is the opposite of what is meant by the question.
In conclusion, the correct answer is A. sparingly. This means using the country’s resources in a careful and economical way.