ANSWER: C
IgAN is the most frequent diagnosis seen in kidney biopsies from patients with renal failure and history of IBD. In a retrospective study performed by Ambruzs et al., the prevalence of IgAN was 24%, followed by TIN (19%), arterionephrosclerosis, ATI, proliferative GN and MCD.

Reference:
Ambruzs JM, et al. The histopathologic spectrum of kidney biopsies in patients with inflammatory bowel disease. 2014 Clin J Am Soc Nephrol; 9(2):265-270.