The most common cause of delayed umbilical cord separation is
Leukocyte adhesion deficiency may present with recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. All other options given are various umbilical pathologies, but not related to delayed sloughing of cord
Raspbery tumour
Leukocyte adhesion deficiency
Patent urachus
Umbilical granuloma
General anatomy