Which one of the following statements about alkaline earth metals is not true?

• A. Strontium salts burn with a red flame
• B. Barium metal is used in medicine to examine the alimentary canal of a patient by X-ray
• C. Green plants need magnesium in order to make the chlorophyll that trap the energy from sunlight in photosynthesis
• D. Red color of gemstone Ruby is due to the element beryllium present in it