Final Answer:
The biggest disadvantage of vegetative propagation is c) Vulnerability to diseases, as genetically identical plants are more susceptible to the spread of diseases and pests. Therefore, the correct option is c.
Step-by-step explanation:
Vegetative propagation involves creating new plants from existing ones without the involvement of seeds. While this method ensures that the offspring are genetically identical to the parent plant, it also presents a significant drawback in terms of susceptibility to diseases. Since all plants produced through vegetative propagation share the same genetic makeup, they lack the genetic diversity that can provide resistance to various pathogens.
The absence of genetic diversity makes these plants more vulnerable to diseases and pests. If a particular pathogen can successfully infect one plant, it is likely to affect all plants that are genetically identical. This lack of variability in the gene pool limits the plants' ability to adapt to changing environmental conditions and evolving threats, increasing the risk of widespread damage in the case of an outbreak.
In contrast, sexual reproduction, which involves the fusion of gametes and the formation of seeds, introduces genetic variation, promoting diversity within plant populations.
This diversity acts as a natural defense mechanism, as some plants may possess traits that make them resistant to specific diseases or pests. Therefore, while vegetative propagation offers benefits such as maintaining desirable traits in plants, the reduced genetic diversity poses a significant disadvantage in terms of plant health and resilience.
Therefore, the correct option is c.