This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Embryology, Subject name: Anatomy
Homeobox gene is responsible for: 
Select and explain. 
A. Segmental organization of embryo in craniocaudal direction, B. Proper organization along dorsal ventral axis, C. Stimulation for lengthening of limbs, D. All of the above
A: Segmental organization of embryo in craniocaudal direction
Answer: A: Segmental organization of embryo in craniocaudal direction 
Explanation: Ans. A Segmental organization of embryo is craniocaudal directionRef: Netter's Atlas of Human Embryology, 2012 ed. pg. 10* Homeobox (HOX) gene is involved in segmental organization of embryo in cranio-caudal direction. The mutation in gene leads to formation of appendages in wrong locations.* Sonic hedge-hog gene is involved in patterning in A-P axis. The mutation in this gene leads to holoprosencephaly.