Maybe c or d
Step by step:
Rickets is caused as a result of vitamin D deficiency. The role of vitamin D in the body is its significance in the absorption of phosphorus and calcium from the gut. Consequently, phosphorus and calcium in the blood is absorbed in the extracellular matrix of bone hence giving them strength. Therefore, deficiency of vitamin D results to soft bones that are a symptom of rickets.
Answer:
If the mantle is made out of soft rock, then I think it would melt due to the heat, but if it was hard, it would just burn, so I firmly believe the rock is hard.
Explanation: