Answer:
They cut (restrict) DNA only at a particular recognition sequence within it.
Step-by-step explanation:
The restriction enzymes or restriction endonuleases are types of nuclease enzymes that cleave larger DNA molecule into smaller fragments. These enzymes recognize specific sequence on DNA and cleave it at or near that sequence. These sequences are known as restriction sites.
EcoRI is an example of restriction enzyme that recognizes and cleaves at sequence G/AATTC.
Thus, the correct answer is first option.