The transition phase between regular menstrual periods and no periods at all is known as a. menarche b. puberty c. metrorrhea d. perimenopause

The right option is d. ​Perimenopause

Perimenopause is the transition phase between regular menstrual periods and no periods at all. It takes place over several years in advance of the menopause. Perimenopause generally starts for women in their mid-40s and it can start even earlier.  Symptoms of Perimenopause include fatigue, breast tenderness, irregular periods and mood swings.

thermophiles, notice the prefix thermo.