A lichen is made up of an alga and a fungus . Which of the following provides the best evidence that the relationship between the alga and the fungus in the lichen is mutualistic ? The alga and the fungus belong to different kingdoms . The alga and the fungus both require moist environments . The alga is a simple unicellular organism, and the fungus is a complex multicellular organism. The alga provides sugars for the fungus, and the fungus provides structure and protection for the alga. B C or D

The best evidence that the relationship between the alga and the fungus in the lichen is mutualistic is option D: The alga provides sugars for the fungus, and the fungus provides structure and protection for the alga. This demonstrates a mutually beneficial interaction, where both the alga and the fungus rely on each other for essential resources and support.