Which of these is a unique feature of IHOP's menu offerings?

The unique feature of IHOP's menu offerings is the all-you-can-eat pancakes. This option highlights IHOP's emphasis on pancakes, which are a core part of their brand identity. The all-you-can-eat pancake promotion showcases IHOP's commitment to providing an abundant and satisfying dining experience centered around this iconic dish.

In contrast, the option that states only breakfast items are served is not accurate since IHOP offers a variety of meals beyond breakfast, including lunch and dinner items. A focus on steak and seafood is not a characteristic feature of IHOP, as the brand is most renowned for its breakfast offerings, particularly pancakes and waffles. Lastly, the mention of a full vegan menu does not align with IHOP's typical offerings, as they are primarily known for their traditional American diner-style menu without a comprehensive vegan selection. Thus, the all-you-can-eat pancakes truly set IHOP apart in their menu offerings.