The purpose of the clock in a digital circuit is Select one: O a. To tell the logic gates when their outputs are valid O b. To make all the flip flops update their state at the same time O c. To keep track of the time of day Which statement is NOT true? Select one: O a. A register file can only change the state of a register at a clock tick O b. A register file uses a demultiplexer to determine which register to load O c The number of registers in a register file must be a power of 2 O d. A register file can hold some variables in a computer program e. A register file uses a multiplexer to determine which register to read out f. A register file can load a register in the middle of a clock cycle