Final answer:
The third category of DNA sequences is called moderately repetitive DNA, which includes elements like SINEs, LINEs, and VNTRs.
Step-by-step explanation:
The third category of DNA sequences in a eukaryotic genome, besides highly repetitive and unique sequences, is called moderately repetitive DNA. This category includes types of elements such as Short Interspersed Nuclear Elements (SINEs), Long Interspersed Nuclear Elements (LINEs), and Variable Number Tandem Repeats (VNTRs). These elements are usually found throughout the genome and can have various roles, such as regulating gene expression and increasing genetic diversity within a species.