Find the odd vegetable item (botanical category): Select the item that is botanically a fruit, not a root, tuber, or bulb.

Introduction / Context:
Although all four are common “vegetables” in cooking, botanically they differ. One is a fruit, while the others are underground parts such as root, tuber, or bulb.

Given Data / Assumptions:

• Tomato: botanical fruit (ripened ovary with seeds).
• Potato: tuber (modified underground stem with buds/eyes).
• Carrot: taproot (storage root).
• Onion: bulb (underground storage structure).

Concept / Approach:
Apply botanical classification rather than culinary use. Fruits develop from flowers and carry seeds; the others are subterranean storage/vegetative structures.

Step-by-Step Solution:

Verification / Alternative check:
Seed presence: tomatoes contain seeds; roots/tubers/bulbs do not develop seeds within the edible portion.

Why Other Options Are Wrong:
They belong to vegetative underground categories, creating a unified set distinct from fruits.

Common Pitfalls:
Do not rely on kitchen categories; stick to plant morphology.

Final Answer:
Tomato