Which of these corresponds to layer 2 (data link)?

a. Governs hardware connections and byte-stream encoding for transmission.

b. Splits data into packets to be sent across the connection medium (data framing).

c. Defines protocols for routing data by opening and maintaining a path on the network between systems to ensure that data arrives at the correct destination node.

d. Ensures that packets have no errors and that all the packets arrive and are in the correct order.