A DNA molecule in which both strands have radioactive thymidine is allowed to duplicate in an environment containing non-radioactive thymidine. What will be the correct number of DNA molecules that contain some radioactive thymidine after three duplications [AIIMS 1980; DPMT 1993]

• A. There will be four such molecules
• B. There will be eight such molecules
• C. There will be only one such molecule
• D. There will be two such molecules