Correct answer: (a) 1 2 3 4
Explanation
- A
1 2 3 4
(a) 1 2 3 4. Uzbekistan’s capital is Tashkent; Tajikistan’s is Dushanbe; Kyrgyzstan’s is Bishkek; Turkmenistan’s is Ashgabat. The list is already in that order, so the straight code is the official key.
- B
1 2 4 3
(b) 1 2 4 3. It swaps Bishkek and Ashgabat, giving Kyrgyzstan Turkmenistan’s capital.
- C
1 3 4 2
(c) 1 3 4 2. Dushanbe is moved off Tajikistan and Bishkek is parked on the wrong republic.
- D
1 4 2 3
(d) 1 4 2 3. Ashgabat is given to Tajikistan. Turkmenistan’s white-marble capital must stay on Ashgabat.
Summary. Official key is (a) 1 2 3 4. Four Central Asian capitals are one-to-one: Tashkent, Dushanbe, Bishkek, Ashgabat. Any code that swaps Bishkek with Ashgabat or Dushanbe with another city fails. Honour the stored letter (a).