The following plot shows the effect of temperature on the modulus of two polymers, "X" and "Y". 

Answer the following questions in the space below:

a) What type (or class) of polymers are "X" and "Y". Explain your answer.

b) Give a specific example for each type of polymer.

c) If the service temperature of a component is between 50 °C and 120 °C, which polymer is more suitable? Explain your answer. 

d) Explain the importance of the rubbery regions for both "X" and "Y" and relate this to the type of bonding present in the polymers.