In 1960 which of the following contributed most directly to soviet leader nikita khrushchev's cancellation of a scheduled summit meeting with president dwight d. eisenhower? :
a. the rise to power of fidel castro in cuba.
b. the failure, at the bay of pigs, of a u. s.-sponsored attempt to oust fidel castro.
c. the downing of an american u-2 spy plane over the soviet union.
d. the sending of u. s. troops to lebanon.
e. the success of the soviet space program in launching the sputnik satellite.

C. the downing of an American U-2 spy plane over the Soviet Union.

The downing of the American spy plane in Soviet Union named U-2 contributed mostly to the cancellation of a scheduled summit between the Soviet Union's leader Nikita Khrushchev and that of President Dwight D. Eisenhower.

In 911, a group of vikings lead by rollo besieged paris and chartres. after a victory near chartres on 26 august, charles decided to negotiate with rollo. the talks were led by hervé, the archbishop of reims. this resulted in the treaty of saint-clair-sur-epte, which granted rollo and his soldiers all the land between the river epte and the sea. it also granted him brittany, "for his livelihood". at the time, brittany was an independent land which france had not been able to conquer. in exchange, rollo promised the king his loyalty and military assistance when needed. also rollo also agreed to be baptised and to marry gisela, the king's daughter. the territory given rollo is about the same as upper normandy.