The correct answer is: C. To transform data into a higher-dimensional space for better separability.
The kernel trick is a technique used in support vector machines (SVMs) to transform data into a higher-dimensional space where the data points are more linearly separable. This can be done using a kernel function, which is a mathematical function that maps data points from a lower-dimensional space to a higher-dimensional space. The kernel trick allows SVMs to be used with non-linearly separable data.
Option A is incorrect because the kernel trick does not create decision boundaries. Decision boundaries are created by the support vectors, which are the data points that lie on the margin between the two classes.
Option B is incorrect because the kernel trick does not visualize data. Visualization is done using techniques such as scatter plots and multidimensional scaling.
Option D is incorrect because the kernel trick does not reduce the dimensionality of data. Dimensionality reduction is done using techniques such as principal component analysis and singular value decomposition.