Which of the following are all red varieties of seaweed?

The selection of dulche, Irish moss, and laver as red varieties of seaweed is accurate due to their classification within the Rhodophyta, or red algae, family.

Dulse (Palmaria palmata) is a popular red seaweed, known for its nutritional benefits and is commonly used in various dishes. Irish moss (Chondrus crispus) is another red seaweed that is often used as a thickening agent in foods and has a long history of culinary use. Laver (Porphyra spp.) is also a red seaweed, frequently used to make nori, the seaweed sheets that wrap sushi.

In contrast, some other options include seaweeds that do not belong to the red category. Nori, for instance, is a type of laver but is generally classified in a way that relates it more closely with the harvesting methods rather than solely its color classification. Kombu and kelp, found in these options, are both brown algae (Phaeophyceae) and do not fit into the red category, hence they would not qualify as red varieties of seaweed.