Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[EX Q]: ayman al-zawahiri is a former member of islamist organizations which have organised and carried out attacks in north america, asia, africa and the middle east.
[EX A]: ayman al-zawahiri

[EX Q]: a releaser is a stimulus from one animal to another, which causes a particular response.
[EX A]: releaser

[EX Q]: ricardo de la espriella toral (born september 5, 1934) is a panamanian politician.
[EX A]:
ricardo de la espriella