What is the reason that some elements are formed inside stars and nowhere elsea.

I think it would be answer B or D  . I gave you two answer because I dont want to be wrong with one

Puberty stage include different types of changes including cognitive (emotional), physical (voice, pubic hair, genitalia, etc.) and physiological (synthesis of sex steroid hormones) modifications

Explanation:

Physical puberty changes in girls occur from ages 10  to 14 and they are associated with the growth of pubic and underarm hair, breast development, and the first menstrual period (known as menarche). In boys, puberty occurs from ages 10 to 20, being this period associated with the growth of the testicles, the growth of pubic hair, changes in the voice, presence of sperms in the seminal fluid, etc.

Puberty hormones:  

     - Boys and girls: gonadotrophin-releasing hormone (GnRH) required for the production of Follicle Stimulating (FSH) and Luteinizing (LH) hormones

     -Boys: testosterone  

     -Girls: estrogen