What is a single stack of thylakoids inside a chloroplast called?

1. A chloroplast has an outer and an inner membrane like a mitochondrion. 2. Inside the inner membrane sit interconnected, stacked, fluid-filled membrane sacs called thylakoids. 3. Each stack of those thylakoids is a granum, and the plural is grana. 4. A crista is a fold of the mitochondrial inner membrane, so it belongs to a different organelle. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 4 "Cell Structure", section 4.3 Eukaryotic Cells_