Answer:
Option A is correct!
Explanation:
Since 3n is even number and we know that previous and next number of an even is always an odd number
here the first option is 3n-1 which means one less than 3n that means the number previous to 3n so it is odd .
3n-2 means 2 number lesser than 3n which is again even number.
same argument will be given for 3n+2
2n means even number because n is multiple of 2
sum of two even is again even therefore 32n is again even.