50. The polymerase chain reaction (PCR) is a powerful technology to amplify DNA. If the detection sensitivity of DNA agarose gel is 10s molecules of double-stranded DNA and the starting material contains 100 double-stranded DN A molecules, what is the minimal number of PCR cycles to detect the DNA by agarose gel electrophoresis? (assume the efficiency of every PCR cycle is 100%) (A) 5 (B) 8 (C) 10 (D) 16 (E) 32