Question: When did the  Union of South Africa start using Dutch (the one whose pronunciation audio is Nl-Nederlands.ogg) as the official language?
Choices: 1910-05-31
1990-10-04
2007-12-02
1950-09-28
1936-07-18
1978-09-17
2001-10-16
1934
2003-06-05
1991-07-20
SPARQL: SELECT DISTINCT ?qpv WHERE { ?e_1 <pred:name> "Union of South Africa" . ?e_2 <pred:name> "Dutch" . ?e_2 <pronunciation_audio> ?pv . ?pv <pred:value> "Nl-Nederlands.ogg" . ?e_1 <official_language> ?e_2 . [ <pred:fact_h> ?e_1 ; <pred:fact_r> <official_language> ; <pred:fact_t> ?e_2 ] <start_time> ?qpv .  }
Program:
function: Find
inputs: Union of South Africa
function: Find
inputs: Dutch
function: FilterStr
dependencies: 1
inputs: pronunciation audio
Nl-Nederlands.ogg
function: QueryRelationQualifier
dependencies: 0
2
inputs: official language
start time
Answer: 1910-05-31