Rickets is:
a) A deficiency disease resulting from a lack of vitamin D or calcium and from insufficient exposure to sunlight, characterized by defective bone growth and occurring chiefly in children
b) A disease occurring primarily in adults that results from a deficiency in vitamin D or calcium and is characterized by a softening of the bones with accompanying pain and weakness
c) A disease characterized by a decrease in bone mass and density, occurring especially in postmenopausal women, resulting in a predisposition to fractures and bone deformities such as a vertebral collapse
d) All of the above
