Answer: B). If you read them from left to right, one strand runs 5’ to 3’, and the other runs 3’ to 5’.
Explanation: Being antiparallel means that one of the two strands runs in 3’->5’ direction while the other runs in a 5’->3’ direction. The antiparallel nature of the two DNA strands makes DNA synthesis to be semidiscontinous. Because DNA synthesis always proceeds in the 5’->3’ direction, the leading strand is synthesized continuously while the lagging strand is synthesized discontinuously in short pieces called Okazaki fragments. The continuous or leading strand is the one in which 5’->3’ synthesis proceeds in the same direction as replication fork movement while the discontinuous or lagging strand is the one in which 5’->3’ synthesis proceeds in the direction opposite to the direction of fork movement.
