Explanation

Pakistan joined Commonwealth in 1947, left in 1972, and rejoined in 1989

So according to the option, "1989 is correct"

British Commonwealth  Pakistan emerged as an independent state on 14th August 1947.

Pakistan joined other "Organizations"

Pakistan joined FAO on 7 September 1947.

Pakistan joined UNESCO on 14 September 1949

Pakistan joined World Bank in 1950.

Pakistan joined IMF on 11 July 1950 

Pakistan joined SEATO in 1954.

ND-18-8-2023