Question: When did Frankfurt become the twinned administrative body of Philadelphia whose elevation above sea level is 12 metres?
Choices:
2012-11-13
2015-07-16
1973-12-21
1582-12-07
1972-04-18
2011-04-07
1754-01-01
1961-09-30
2009-10-28
1952-08-14