Step 1: Group Index Method.
The Group Index (GI) method is an empirical method based on soil classification properties. Hence, A → III.
Step 2: CBR Method.
The California Bearing Ratio (CBR) method is an empirical method using soil strength tests. Hence, B → IV.
Step 3: US Navy Method.
This method is semi-theoretical in approach. Hence, C → I.
Step 4: Asphalt Institute Method.
This method is quasi-rational, combining theoretical and experimental approaches. Hence, D → II.
Step 5: Conclusion.
Thus, the correct matching is A - III, B - IV, C - I, D - II. Therefore, the correct answer is (C).
The recommended minimum traffic growth rate and design period considered for structural design of flexible pavements for national highways in India as per IRC 37:2018 is __________ percentage and _________ years, respectively.