Correct Answer - B
Vernalisation is the process of shortening of the juvenile or vegetative phase and hastening flowering by a previous cold treatement. In vernalisation by cold treatement winter varieties are transfereed into spring or summer varieties. Site of vernalisation is apical meristem or all the meristematic cells e.g., shoot tip, embryo tips, root apex etc. Low temperature required for vernalisation is usually `0^(@) -5^(@)C`. As a result of vernalisation, a flowering hormone called vernalion is formed (reported by Melchers), but vernalin has never been isolated.