Concept:Sial is the silica-rich upper layer of the Earth's continental crust, and its density is about 2.7 g/cm³.Explanation:The sial layer is made mostly of silica and alumina, giving it a relatively low density compared with the sima layer beneath it.Its density is commonly given as 2.7 g/cm³, which can also be written as 2700 kg/m³.Looking at the options, the correct match is 2.7.Answer:B. 2.7