Answer:
 c < a = b
Step-by-step explanation:
to arrange tensile stress from smallest to largest
tensile stress = 

a) A rod 50.0 cm long with cross-sectional area 1.00 mm² and with a 200 N force applied on each end.
 

 

 

b) A rod 25.0 cm long with cross-sectional area 1.00 mm² and with a 200 N force applied on each end.
 
 
 
 

 

c) A rod 20 cm long with cross-sectional area 2.00 mm² and with a 100 N force applied on each end.
 

 

 

hence the order comes out to be
 c < a = b