21. During DNA replication, the single-strand DNA-binding (SSB) proteins (A) are generally found more on the leading strand than the lagging strand. (B) bind cooperatively to single-stranded DNA and cover the bases to prevent base-pairing. (C) prevent the folding of the single-stranded DNA. (D) bind cooperatively to short hairpin helices that readily form in the single-stranded DNA. (E) All of the above.