Answer: B. dendrochronology
Dendrochronology is the scientific process of dating growth rings to the exact period they were formed to get information on the age of the tree as well as the previous climate of the area. The branch of dendrochronology however that deals with climatology is referred to as dendroclimatology. Using growth rings, scientists have been able to estimate a variety of local climates for thousands of years previous. As a result of the high sensitivity of growth rings to different climate effects, this makes dendroclimatology effective.