Final answer:
The diagonal approach to global health is best described by utilizing vertical funding to strengthen overall health systems while addressing specific health issues.
Step-by-step explanation:
The diagonal approach to global health involves utilizing vertical funding to strengthen health systems (d). Rather than focusing solely on individual health interventions or diseases, the diagonal approach combines the specificity of vertical programs, such as those targeting specific diseases with funding and resources earmarked for that purpose, with the broader need to enhance the general healthcare system. This methodology works towards improving overall healthcare capacity and infrastructure while also dealing directly with pressing health issues like the spread of infectious diseases, which is a critical concern for low-income countries with high incidences of conditions such as malaria, tuberculosis, and HIV/AIDS. As such, the diagonal approach aims to be a more integrated solution to global health challenges, working to better disease prevention and care within a strengthened healthcare delivery system.