Final answer:
The root 'ger' refers to old age, seen in terms related to the elderly, making the correct answer c) old age.
Step-by-step explanation:
The root ger relates to concepts of old age. This can be seen in words like geriatric, which pertains to the health and care of elderly people, or gerontology, the study of aging and the problems that elderly individuals might face. Therefore, the correct answer is c) old age.
While infancy denotes the very early stage of childhood and is characterised by rapid growth, and adolescent describes the period known as puberty noted for the adolescent growth spurt, neither of these life stages is associated with the root 'ger'.