Among the following options, which are NOT sides of a triangle?

3 cm, 5 cm and 1 cm

Three sides form a triangle iff

Sum of length of two sides > Length of third side

A. 12 cm, 9 cm and 15 cm

( 12 + 9 ) > 15

21 > 15

B. 20 cm, 20 cm and 20 cm

( 20 + 20 ) > 20

40 > 20

C. 3 cm, 5 cm and 4 cm

( 3 + 5 ) > 4

8 > 4

D. 3 cm, 5 cm and 1 cm

( 3 + 1 ) > 5

4 is not greater than 5 .

Answer :- D. 3 cm, 5 cm and 1 cm