What is the core idea behind wavelet-based image compression, as used in formats like JPEG 2000?

A Storing only the pixel differences between consecutive video frames B Encrypting pixel data to deter unauthorized copying of the image C Decomposing the image into multiple resolution levels via wavelet transforms, allowing scalable, progressive compression with fewer blocking artifacts than block-based DCT methods D Splitting the image into fixed 8x8 blocks and applying a discrete cosine transform to each independently