What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?$1.$ DNA polymerase can join new nucleotides only to the $3\text{'}$ end of a growing strand$\mathrm{.}2.$ The origins of replication occur only at the $5\text{'}$ end$\mathrm{.}3.$ Polymerase can work on only one strand at a time$\mathrm{.}4.$ DNA ligase works only in the $3\text{'}-5\text{'}$ direction$5.$ Helicases and single$-$strand binding proteins work at the $5\text{'}$ end.