The correct answer is (b), Turkmenistan.
India held a regional summit on Afghanistan in November 2021. The summit was attended by representatives from Afghanistan, India, Iran, Kazakhstan, Kyrgyzstan, Pakistan, Russia, Tajikistan, and Uzbekistan. Turkmenistan was the only country in the region that did not participate in the summit.
There are a few possible reasons why Turkmenistan did not participate in the summit. First, Turkmenistan has a long history of neutrality and non-alignment. The country has been careful to avoid taking sides in regional conflicts, and it may have felt that participating in the summit would have been seen as a violation of its neutrality.
Second, Turkmenistan has a close relationship with Russia. Russia is a major economic and political partner for Turkmenistan, and the country may have felt that participating in a summit that was also attended by the United States and other Western countries would have strained its relationship with Russia.
Finally, Turkmenistan is a relatively small country with a population of just over 6 million people. The country may have felt that it did not have much to contribute to the summit, and that its participation would not have been very meaningful.
Whatever the reasons for Turkmenistan’s decision not to participate in the summit, it is clear that the country is not as closely aligned with India as the other countries in the region. This could have implications for future cooperation between India and Turkmenistan, and it is something that India will need to keep in mind as it seeks to expand its influence in Central Asia.