Answer:
a. The Curse of Dimensionality
Explanation:
The phenomenon that refers to this is known as the Curse of Dimensionality. This phenomenon is basically the specific complications that only occur when dealing with far larger data sets that contain various dimensions, while these complications do not exist in smaller and less complex data sets. The larger the data set tends to get, the more complications arise. This is usually solved with Dimensionality reduction which shrinks the data sets by targeting specifics of the data and separating it.