Which one of the following vitamins is considered to be a hormone ?

Hormones are chemical messengers produced or activated in the body that exert regulatory effects on target tissues [1]. Vitamin D differs from classical dietary vitamins because it is synthesized in the skin from a cholesterol precursor under UV exposure and is enzymatically converted to the active form 1,25-dihydroxyvitamin D3 (calcitriol), which acts via a nuclear receptor to regulate gene transcription across many tissues. For this reason vitamin D is commonly referred to as the “sunshine” vitamin or a hormone—its active metabolite functions as an endocrine regulator similar to steroid hormones [2]. Therefore, among the options listed, vitamin D is considered to be a hormone.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 6: Control and Coordination > Activity 6.4 > p. 111
2. [2] https://www.nature.com/articles/s41467-020-15421-7