Abnormal/anomalous secondary growth refers to the atypical increase in girth or thickness of a plant stem or root. It occurs due to various factors such as injury, infection, hormonal imbalances, or genetic mutations. In this case, the correct answer is option 'A', Dracaena.

Dracaena is a genus of plants that includes various species commonly known as dragon trees. These plants exhibit abnormal secondary growth, particularly in their stems. Let's delve into the details of why Dracaena shows abnormal secondary growth:

1. Injury:
- Dracaena plants are often grown as houseplants and are pruned to maintain their shape and size.
- Improper pruning techniques or excessive pruning can cause injury to the stem, leading to abnormal secondary growth as a response to the damage.

2. Hormonal Imbalances:
- Hormones play a crucial role in regulating plant growth and development.
- Imbalances in hormone levels, particularly auxins, can disrupt the normal growth patterns and result in abnormal secondary growth in plants like Dracaena.

3. Genetic Mutations:
- Genetic mutations can occur naturally or be induced through genetic engineering techniques.
- These mutations can alter the normal growth patterns of plants, leading to abnormal secondary growth.

4. Environmental Factors:
- Environmental stresses such as extreme temperatures, drought, or nutrient deficiencies can trigger abnormal secondary growth in plants.
- If Dracaena plants are subjected to unfavorable environmental conditions, they may exhibit abnormal growth as a survival mechanism.

It's important to note that while abnormal secondary growth in Dracaena is a natural occurrence, it can also be undesirable in some cases. For example, if the abnormal growth results in distorted or weakened stems, it can negatively affect the overall health and appearance of the plant. Therefore, proper care and maintenance, including appropriate pruning techniques and providing optimal growing conditions, are essential to ensure the healthy growth of Dracaena plants.