Who became the leader of jamestown after john smith?
a) thomas dale
b) john rolfe
c) pocahontas
d) sir walter raleigh

It was "Thomas Dale" who became the leader of Jamestown after John Smith, although it should be noted that depending on the type of authority you're referring to, there was a period where Mr. Gale was in charge. 

(d) it was complex and capable of highly organized efforts.