Solution

Tree locking protocol (graph-based protocol) rules:

• The first lock may be on any node.

• A transaction may lock a node only if it already holds a lock on the parent.

• Nodes may be unlocked anytime but cannot be relocked.

Properties:

• Deadlock cannot occur because locking follows a hierarchical order.

• Transactions can lock data items earlier since unlocking can happen anytime.

Thus:

B → True

C → True