This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

[Q]: Passage: In the mid-1950s, Frank Burnet, inspired by a suggestion made by Niels Jerne, formulated the clonal selection theory (CST) of immunity. On the basis of CST, Burnet developed a theory of how an immune response is triggered according to the self/nonself distinction: "self" constituents (constituents of the body) do not trigger destructive immune responses, while "nonself" entities (e.g., pathogens, an allograft) trigger a destructive immune response. The theory was later modified to reflect new discoveries regarding histocompatibility or the complex "two-signal" activation of T cells. The self/nonself theory of immunity and the self/nonself vocabulary have been criticized, but remain very influential. Question: What property of T cells caused modification of CST?
[A]: the complex "two-signal" activation


[Q]: Passage: Some Christian writers considered the possibility that pagan commentators may have mentioned this event, mistaking it for a solar eclipse - although this would have been impossible during the Passover, which takes place at the full moon. Christian traveller and historian Sextus Julius Africanus and Christian theologian Origen refer to Greek historian Phlegon, who lived in the 2nd century AD, as having written "with regard to the eclipse in the time of Tiberius Caesar, in whose reign Jesus appears to have been crucified, and the great earthquakes which then took place" Question: As what was the event mistaken by some pagans?
[A]: a solar eclipse


[Q]: Passage: Current manager, Roberto Martínez, is the fourteenth permanent holder of the position since it was established in 1939. There have also been four caretaker managers, and before 1939 the team was selected by either the club secretary or by committee. The club's longest-serving manager has been Harry Catterick, who was in charge of the team from 1961–73, taking in 594 first team matches. The Everton manager to win most domestic and international trophies is Howard Kendall, who won two Division One championships, the 1984 FA Cup, the 1984 UEFA Cup Winners' Cup, and three Charity Shields. Question: When did Harry Catterick manage the Everton Football Club?
[A]:
1961–73