Onions grow by vegetative propagation.

Concept: The above-given statement is true.

• You can grow onions from seeds or from bulbs. Vegetative propagation is the practice of growing onions from bulbs. The radicle and flag leaves develop as the bulb expands, and then the actual leaves appear.

The five onion growing stages are:
1. Organization
2. Veggie Development
3. Bulb Initiation

4. Bulb development 
5. Maturation

• Onions produced from transplants go through the aforementioned phases of development. 
• The plants initially develop vegetatively without producing bulbs. The process of bulb development starts after they are a little bit longer and thicker than the transplants.

Hence, option A is the correct answer.