Final answer:
Spark has several demerits, including the lack of support for real-time processing, no built-in file management system, limited data visualization tools, and inefficiency in handling small datasets.
Step-by-step explanation:
One of the demerits of using Spark is that it lacks support for real-time processing, which means it may not be suitable for applications that require immediate data analysis and response. Another limitation is the absence of a built-in file management system, which can make data organization and access more challenging. Spark also has limited data visualization tools, making it less suitable for tasks that require advanced and interactive visualizations. Additionally, Spark may be inefficient in handling small datasets, as its processing overhead can outweigh the benefits of using it for smaller-scale projects.