What condition is characterized by softening and deformity of bones in adults?

The condition that is characterized by softening and deformity of bones in adults is osteomalacia. This disorder occurs due to a deficiency of vitamin D, calcium, or phosphate, which are essential for bone mineralization. In osteomalacia, the bones do not properly mineralize, leading to a softening of the bone tissue, increased risk of fractures, and deformities over time.

In contrast to the other options: osteoporosis primarily involves a loss of bone density and strength, making bones more fragile and likely to fracture, yet does not specifically cause deformities in the same manner as osteomalacia. Osteogenesis imperfecta is a genetic disorder characterized by brittle bones due to collagen deficiencies, while rickets is a similar condition to osteomalacia but occurs in children and involves soft, weak bones due to vitamin D deficiency during their growing years. Thus, osteomalacia is the correct term for the condition affecting adults specifically, which highlights the importance of adequate nutrition and mineral intake for maintaining bone health.