The fifth term of the sequence for which $$t_{1}=1$$, $$t_{2}=2$$ and $$t_{n+2}$$ = $$t_{n}+t_{n+1}$$, is
 $$t_{1}=1$$, $$t_{2}=2$$
 $$t_{n+2}$$ = $$t_{n}+t_{n+1}$$
put n=3, then  $$t_{5}$$ = $$t_{3}+t_{4}$$
$$t_{3}$$ = $$t_{1}+t_{2}$$ = 1+2 = 3
$$t_{4}$$ = $$t_{2}+t_{3}$$ = 2+3 = 5
$$t_{5}$$ = $$t_{3}+t_{4}$$ = 3+5 = 8
so the answer is option D.
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