The following figure shows D flip-flop built from two back-to-back D latches controlled by complementary clocks. Select all the TRUE statements.   Question 1 options: a The D flip-flop is controlled by signal levels. b D flip-flop copies D to Q on the rising edge of the clock, and remembers its state at all other times. c When CLK = 0, L1 latch is transparent and L2 is opaque. Therefore, whatever value was at D propagates through to N1. d When CLK = 1, L1 latch goes opaque and L2 becomes transparent. The value at N1 propagates through to Q, but N1 is cut off from D.