Concept:Use the quantifiers ∃ (there exists) and ∀ (for all) to test each statement against the set A={1,2,3,4,5,6}.Explanation:Option A: ∃x∈A such that x+3=9.For x=6, we get 6+3=9, and 6∈A.So Option A is true.Option B: ∃x∈A such that x+2<9.For x=1, we get 1+2=3<9, and 1∈A.So Option B is true.Option C: ∀x∈A,x+6≥10.But for x=1, we get 1+6=7, and 7≱10.So Option C is false.Option D: ∃x∈A such that x+6<10.For x=1, we get 1+6=7<10.So Option D is true.Answer:The statement which is not true is Option C.