Answer:
Correct answer is C the adoption of a strict moral legal code.
Explanation:
A is not correct because Roman empire had to pay a large amounts of money to maintain the costs of administration and army, and this was especially problematic after they were not able to conquer new territories.
B is not correct as this conflicts were destroying Roman Empire from the inside, especially in the 3rd Century. It brought political and economical decline.
C is correct as this laws were created to prevent the decline of Empire, but it was too late. Diocletian was the one who started this reforms.
D is not correct as they used mercenaries from Germanic tribes, who at the end destroyed the Empire.
