Which diabetic drug classes should be considered in addition to metformin to prescribe for Alfonso and why? 
a) Sulfonylureas and DPP-4 inhibitors to enhance insulin production 
b) Biguanides and SGLT-2 inhibitors to increase glucose excretion 
c) Thiazolidinediones and GLP-1 agonists to reduce insulin resistance 
d) Meglitinides and alpha-glucosidase inhibitors to slow carbohydrate digestion