The correct answer is option 1, Russia. Army Exercise TSENTR, 2019 was hosted by Russia.

Option 1: Russia is the correct answer. The exercise took place in Russia.

Option 2: China is not the correct answer. China did not host the Army Exercise TSENTR, 2019.

Option 3: Kazakhstan is not the correct answer. Kazakhstan did not host the Army Exercise TSENTR, 2019.

Option 4: Kyrgyzstan is not the correct answer. Kyrgyzstan did not host the Army Exercise TSENTR, 2019.

In summary, the correct answer is option 1, Russia.