Final answer:
The correct description for someone who has succumbed to vainglory is 'd) Vain-glorious,' which means an excessive amount of pride in oneself and a strong desire for personal glory.
Step-by-step explanation:
One who has succumbed to vainglory or gluttony may exhibit a self-centered or excessive indulgence in pleasure or vanity. The correct description for someone who exhibits vainglory can be 'd) Vain-glorious,' as this term directly relates to an excessive amount of pride in oneself or one's achievements, and a strong desire for personal glory. On the other hand, someone who succumbs to gluttony can also be described as 'Hedonistic,' which refers to the pursuit of pleasure as the sole or chief good in life. However, since the question specifically includes 'vainglory,' the most fitting description would be 'vain-glorious.'