Final answer:
In the PICO format, the 'C' represents the Comparison group, which could be standard care, a placebo, or no treatment. For the given options, 'Standard care for women with diabetes' is the correct representation of the 'C'.
Step-by-step explanation:
When using the PICO format to formulate a clinical question, the 'C' stands for the Comparison or control group. In this context, the comparison or control group is what the new treatment or intervention is being compared against. It can include standard care, a placebo, or no treatment at all. For the question at hand, option 'd' - Standard care for women with diabetes - represents the 'C' because it is what the new treatment would be compared against to determine its efficacy.