The correct option is "1 and 2 only" because Blu-ray Discs (BD) are specifically designed to support high-definition (HD) video, offering significantly improved visual clarity compared to standard-definition DVDs. Additionally, the storage capacity of a Blu-ray Disc is substantially higher, typically 25 GB per layer compared to 4.7 GB for a single-layer DVD, allowing for more data such as higher-quality video and additional features. The thickness of the discs, although a detail, is not a primary distinguishing factor in the functionality and usage of the formats, and therefore does not warrant inclusion in the correct statements. This understanding is crucial for recognizing the technological advancements in media formats and their implications for content consumption and dissemination.