Which of the following method is best for age determination of animal?

Dentation is best for age determination of animals.
Cattle dentition is generally used as an indicator of age when actual birthdates are not available. Eruption times and wear of the teeth are the major factors used to estimate bovine age.
The central pair of temporary incisors are replaced by permanent ones which attains full growth by 2 years. The fourth permanent incisors erupt after 30 months. The second pair of incisors is fully developed at 3 years.