複選題29. Which of the following statements regarding DNA is (are) CORRECT? (A) DNA replication in cells uses the original double-stranded DNA (dsDNA) as a template. Regardless of direction, the choice of which strand is used as the template for leading strand or Okazaki fragment synthesis is by chance. (B) The dsDNA duplex adopts the B-form structure, which features two different sizes of grooves known as the major and minor grooves. (C) Due to hydrogen bonds formed between base pairs, the DNA double helix is flexible along its long axis, allowing it to bend when complexed with DNA-binding proteins. (D) In E. coli, the structure of dsDNA is supercoiled. (E) DNA concentration is commonly measured by absorbance at 260 nm, as the absorbance value reflects the amount of phosphodiester bonds.