Final answer:
Lack of calcium and vitamin D in children leads to rickets, and in adults, it contributes to osteomalacia, eventually causing osteoporosis. The correct answer is A) Rickets, Osteoporosis.
Step-by-step explanation:
The condition in children caused by a lack of calcium and vitamin D is called rickets, which leads to improper bone development and can result in bone deformities. The same deficiency in adults can cause osteomalacia, which is the softening of the bones, and contributes to osteoporosis, a condition characterized by weak and brittle bones. Therefore, the correct answer to the question is A) Rickets, Osteoporosis.