Answer: C

Reasoning: Primary molars have long, thin and widely flared roots.  
• Because the apices are spread far apart, osteoclastic activity can bypass some areas; it is not unusual to find un-resorbed apical thirds persisting even late in the exfoliative phase [Rimondini, 1995, PMID 7641630].  
• The same flaring makes these thin apical thirds very liable to fracture when the tooth is luxated or rotated during extraction; divergent or extremely curved roots are a well-documented risk factor for intra-operative root tip fracture [Shmuly, 2022, PMID 35765135].  

Thus both problems (A and B) are associated with wide root divergence → option C.