Infantile amaurotic idiocy $(Tay-Sachs disease)$ is

• A
  The result of severe protein deficiency in diet and damages the muscle development in growing children
• B
  An inherited disorder in which the spinal cord and brain are severely damaged within a few months of birth leading to paralysis and mental retardation,and finally the infant's death in $3$ or $4$ years
• C
  $A$ genetic abnormality which appears at the age of $25-30$ years and damages the bones
• D
  $A$ chromosomal disorder in young children