The enzyme that makes new strands of dna only in one direction is: primase
a- it adds a primer dna ligase
b- it seals the strands together dna polymerase
c- it builds the new strands from 5' to 3' helicase
d- it unzips the strands

Option C

Explanation:

Primase synthesizes DNA polymerase through the initiation of synthesis of RNA primer. DNA polymerase is able to add nucleotides in only one direction towards the direction of replication fork Hence, it add to the chain only at 3’ end  and build new strand from 5’ to 3’ end.  

The 5’ to 3’ strand is the leading strand and is easy to build as 5’ to 3’ progresses towards the replication fork and DNA polymerase also move in the same direction

Hence, option C is correct

the scientific method.