To determine the voltage \(V_o\) in the given circuit, we need to analyze the behavior of the diodes \(D_1\) and \(D_2\).

1. Forward Voltage of \(D_2\): Diode \(D_2\) has a forward voltage drop of \(0.7 \, V\). This means that \(D_2\) will conduct when the voltage across it exceeds \(0.7 \, V\).
2. Zener Diode \(D_1\) Characteristics: The zener diode starts conducting when the reverse voltage is greater than \(2.7 \, V\). For voltages lower than this, it operates in reverse-biased mode without conducting significant current.
3. Circuit Analysis:
   • The supply voltage is \(3.7 \, V\).
   • \(V_o\) is the voltage over the 1 kΩ resistor and diode \(D_2\).
   • Since \(D_1\) is reverse-biased initially and will not conduct until it reaches its zener breakdown voltage of \(2.7 \, V\), it has no effect initially.
   • Given the forward drop of \(D_2\) (0.7 V), the remaining voltage will drop across the 1 kΩ resistor and \(D_2\).
   • The voltage across \(D_2\) is 0.7 V, and hence the voltage at \(V_o\) must satisfy:
   • \(V_o = 3.7 \, \text{V} - 1 \, \text{k}\Omega \times I_{\text{forward}} - 0.7 \, \text{V} = 2.2 \, \text{V}\)

Thus, the voltage \(V_o\) across the 1 kΩ resistor and \(D_2\) is 2.2 V, which matches the given correct option.