Final answer:
The correct biconditional statement is c) pt.
Step-by-step explanation:
The correct biconditional statement is c) pt. Option a) is a correct biconditional statement because it states that being both right and happy are dependent on each other. Option b) is also a correct biconditional statement because having a linear pair and having adjacent angles on a line are equivalent conditions. Option d) is a correct biconditional statement because angles that sum to 90° are complementary to each other.