Statistics

The answer is P(X<=10)=1

A is wrong because X can take 11 values from 0 to 10.
B is wrong because it is counting P(x=5) twice. P(x>=5) + P(x<5) does equal one.
C is wrong because P(x<6) does not include P(x=6)
D is wrong because it excludes P(x=2). Correct would be P(x<=4) - P(x<2)
E is correct. If you do ten trials and count the successes, the probability you will have 10 or less successes is 100%