29. Consider the following statements regarding hold circuits for the reconstruction of sampled signals: 1. Hold circuits are essentially low-pass filters. 2. A first-order hold circuit introduces less phase-lag in comparison to zero hold circuit 3. A zero-order hold has a flat gain-frequency response over the frequency range 0 v 2=T, where T is the sampling period. Which of the following is correct? (a) 3 alone (b) 1 and 2 (c) 2 and 3 (d) 1 alone