1)as my age is 21 year my bp is 145/80 using atenolol 25 mg for 6 months 2)now dr prescribed me nebivolol 2.5 it works perfectly bp is in 120/70 3)which beta-blocker have safest for my age group nebivolol, bisoprolol, atenolol etc.

Beta blockers: I'm not a fan of using beta blockers as first line treatment of hypertension unless the patient tends to have a fast resting heart rate or has coronary artery disease. However, since you're doing well on nebivolol and not having the side effect of fatigue, I think it's very effective for you and shouldn't prevent your heart rate from increasing appropriately during exercise unlike other beta block