Limestone is a common form of calcium carbonate. When limestone is subjected to high heat, it becomes calcium oxide and releases carbon dioxide gas. This change in limestone, at a given temperature, is an example of: A. a physical change like the melting of ice

B. a chemical change like the rusting of iron

C. an igneous change like the melting of rock in a volcano

D. a reversible change such as hardening melted butter

Recent research by marine biologists suggests that bottlenose dolphins have names for themselves. scientists played sounds they had identified as the names of particular dolphins, putting them through a synthesizer so that they did not sound like the voices of particular dolphins. the researchers found that dolphins would respond to the names of other dolphins that they were related to or associated with, but they ignored the names of strangers. this discovery suggests a much greater degree of self-awareness in aquatic mammals than was previously suspected. if this research holds up, what does it suggest about dolphins?