Which of the Following Is a Technique Used to Encourage

Multiple Choice

Which of the following is a technique used to encourage bacteria to take up DNA from the surrounding culture medium?

A) pretreatment of bacteria with a brief heat shock, followed by exposure to Ca²⁺ ions
B) pretreatment of bacteria with Cu²⁺ ions, followed by a brief heat shock
C) pretreatment of bacteria with Ca²⁺ ions, followed by a brief heat shock
D) pretreatment of bacteria with Ca²⁺ ions, followed by a brief cold shock
E) pretreatment of bacteria with a brief heat shock, followed by exposure to Mg²⁺ ions