A pavement designer has arrived at a design traffic of $100$ million standard axles for a newly developing national highway as per $IRC:37$ guidelines using the following data: design life $=15$ years, commercial vehicle count before pavement construction $=4500$ vehicles/day, annual traffic growth rate $=8\%$. The vehicle damage factor used in the calculation was

1. $1.53$
2. $2.24$
3. $3.66$
4. $4.14$

Answer: