o,Ncite eht smte yass oeo"srpscrr ni hte ksin"
D3 ecricca)llfhooe(l mofr xeesourp fo sink a(tmtrus asl)bae to uns, iitgenosn of sih,f mikl, p.ltsan
D2 faceri)gcoerl(ol rmof intoinesg of al,ntps nu,fgi s.easyt
otBh rdteecvon to 2O5-H D3 teasog(r o)mrf in verli nad ot the vaiect rmof 51,2)H(2O- D3 tioa)(llcrci in .ikeydn
The key bit in this question that makes the answer Cholecalciferol rather than 7-dehydrocholesterol is the nugget that the patient "rigorously avoids exposure to the sun." Conversion of 7-dehydrocholesterol to Cholecalciferol can only occur when the skin is exposed to sunlight. Therefore, decreased production of Cholecalciferol (D3) is the better answer.
This picture always helps me remember Vitamin D metabolism.