Which of the following factors increases the creep tendency of materials?

The factor that increases the creep tendency of materials is time. Creep is defined as the slow, gradual deformation of materials under constant stress over an extended period. Essentially, as time progresses, materials experience internal changes due to the applied load, which leads to the accumulation of plastic deformation.

In high-temperature applications, the atomic structure of materials begins to move due to thermal energy, and over time, this movement results in the material elongating or changing shape. Thus, the longer the material is subjected to stress at elevated temperatures, the more pronounced the creep effect will be.

Other factors such as temperature and the nature of the material can also play significant roles in determining creep behavior, but in the context of this question, time is the primary factor that directly correlates with the increase in creep tendency.