The correct answer is: B. 30 days
The 4500 kms BPC is valid for 30 days from the date of purchase. This means that you can use it to travel up to 4500 kms within 30 days of purchasing it. If you do not use it all within 30 days, the remaining balance will be forfeited.
Option A is incorrect because it states that the 4500 kms BPC is valid for 12+3 days. This is not correct because the 4500 kms BPC is valid for 30 days from the date of purchase, not 12+3 days.
Option C is incorrect because it states that the 4500 kms BPC is valid for 45 days. This is not correct because the 4500 kms BPC is valid for 30 days from the date of purchase, not 45 days.
Option D is incorrect because it states that the 4500 kms BPC has no limit. This is not correct because the 4500 kms BPC is valid for 30 days from the date of purchase.