You Are Troubleshooting a TTL Circuit Board Containing Dozens of IC

You are troubleshooting a TTL circuit board containing dozens of IC chips. You have taken several readings at numerous IC chips but the readings are inconclusive because of their erratic nature. Assuming the circuit worked properly at one time, what is the most likely cause of the problem?

A) A solder bridge between the inputs on the first IC chip on the board
B) An open connection between the inputs on the first IC chip on the board
C) A defective output IC chip that has an internal open to V_cc
D) A defective IC chip that is drawing excessive current from the power supply