Which of the following would be an example of a seasonal ingredient?

Pumpkin in autumn is indeed a prime example of a seasonal ingredient due to its peak growing season in the fall, which typically spans from late summer to early autumn. During this time, pumpkins are at their freshest and most flavorful, often harvested in September and October. In many culinary traditions, they are associated with autumn dishes and holidays such as Halloween and Thanksgiving, making them a celebrated ingredient during this season.

The other ingredients listed do not align as closely with a traditional seasonal pattern. Avocados and mangoes are typically available year-round in many regions, especially with modern agricultural practices. Tomatoes, while often considered summer vegetables, can sometimes be found in markets during winter due to greenhouse production; however, they are generally best in the warmer months. Therefore, when evaluating for seasonality, pumpkin stands out as the clear seasonal ingredient, aligning with the natural harvest cycle and culinary traditions of autumn.