Correct : A

Case 1 — V_WX1 = 100V applied, find V_YZ1 (open circuit):
Transformer steps up: secondary voltage = 100 × 1.25 = 125V
Attenuator output (open circuit YZ): V_YZ1 = 125 × 0.8 = 100V
V_YZ1/V_WX1 = 100/100 = 1.00
Wait — but the attenuator factor of 0.8 applies only when it is loaded. Under open circuit, an attenuator''s output equals its input (no current flows, no voltage drop across the series resistor).
Looking at the circuit image more carefully: the attenuator is a resistive network (likely a π or L-pad) connected between the transformer secondary and YZ. Under open circuit at YZ, the series resistors in the attenuator carry no current, so no voltage drop — the full secondary voltage appears at YZ.
Case 1 — open circuit at YZ:
Transformer output = 100 × 1.25 = 125V
Attenuator open-circuit output = 125V (no load, no voltage drop)
V_YZ1 = 125V
V_YZ1/V_WX1 = 125/100 = 1.25
Case 2 — V_YZ2 = 100V applied at YZ, find V_WX2 (open circuit):
V_YZ2 = 100V applied at YZ with WX open.
The attenuator now passes signal from YZ toward transformer. Under open circuit at WX (no current from transformer primary side), the attenuator sees no load on its output side (transformer secondary open since primary is open).
Input to transformer secondary = 100V (no drop in attenuator with no load)
Transformer steps down: V_WX2 = 100 × (1/1.25) = 100 × 0.8 = 80V
V_WX2/V_YZ2 = 80/100 = 0.80
So: V_YZ1/V_WX1 = 125/100 and V_WX2/V_YZ2 = 80/100
Correct answer: A — 125/100 and 80/100. Your page''s answer of D (80/100 and 80/100) is WRONG. Explanation for website: The circuit has an ideal transformer with turns ratio 1:1.25 on the WX side, followed by a resistive attenuator (factor 0.8) on the secondary side, with output terminals YZ.
Case 1 — V_WX1 = 100V, YZ open circuit:
The transformer steps up the voltage: secondary = 100 × 1.25 = 125V. Since YZ is open, no current flows through the attenuator''s series resistors, so there is no voltage drop. V_YZ1 = 125V.
V_YZ1/V_WX1 = 125/100
Case 2 — V_YZ2 = 100V, WX open circuit:
Signal travels from YZ back through the attenuator toward the transformer. With WX open, no current flows in the transformer primary, so the transformer secondary is effectively open. No current flows through the attenuator from YZ side either, so no voltage drop in the attenuator. Full 100V reaches transformer secondary. Transformer steps down: V_WX2 = 100/1.25 = 80V.
V_WX2/V_YZ2 = 80/100
Correct answer: A — 125/100 and 80/100.