Relationship between vitamin b12,b6 deficiency and homocystinuria

The answer is A because in a life cycle it start of in birth, then growing up, then adult then giving birth and then death. after death or birth the life cycle starts all over again. but in actuality when it gives birth that's when the life cycle is restarted. think as it's us humans. we are born. after that we grow up to be a toddler - young kid => teenager => young adult => then women gives birth => new baby is born. when new baby is born then the life cycle is restarted. but the next step after a baby's born the mom and dad get old and then death is the last step.