Which two statements contradict each other?

i. lies on plane pqr.
ii. point s lies on plane pqr.
iii. does not lie on plane pqr.

a. i and ii

c. ii and iii

d. no two of the statements contradict each other.

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?