Through their experiments with DNA from the bacterium Escherichia coli, Meselson and Stahl showed that DNA replication is A: conservative.； B: dispersive； C: duplicative.； D: semi-conservative 

What type of technique is FTIR spectroscopy? ( ) A: A dispersive technique B: An emission technique C: An absorbance technique D: A UV-Vis technique E: A reflectance technique