the diagram shows you triangle def with de=4, df=9 and de≠df≠ef.
the sum of the lengths of two triangles' sides are always greater than the length of the third side:
de+df> ef (option 54 is false); de+ef> df (option 1 is true); ef+df> de.
substitute sides lengths:
4+9> ef ⇒ ef< 13; 4+ef> 9 ⇒ ef> 5.
then 5< ef< 13 (option 3 is true).
def is a scalene triangle with all sides of different lengths (option 5 is true, option 2 is false).
answer: correct choices are 1, 3 and 5