**Explanation:**

The creep test is a type of mechanical test used to determine the behavior of a material under a constant load over an extended period of time. It is used to study the phenomenon of creep, which is the time-dependent deformation of a material under a constant stress.

The type of stress applied to the specimen in the creep test is uniaxial tension. This means that the specimen is subjected to a constant tensile load in one direction, while the other dimensions of the specimen are constrained.

**Reasons for the Correct Answer:**

- Uniaxial tension is the most common type of stress applied in the creep test because it allows for a controlled and consistent loading condition.
- The applied tensile stress causes the material to elongate over time, and the amount of elongation is measured at specified time intervals.
- This allows for the determination of the creep behavior of the material, including the creep rate and the steady-state creep rate.
- Uniaxial tension is chosen over other types of stress, such as compression or alternating stress, because it is easier to apply and measure in a laboratory setting.
- Biaxial compression or tension involves applying stress in more than one direction, which adds complexity to the test setup and analysis.
- Alternating stress involves cyclic loading and unloading, which is not suitable for studying the time-dependent deformation of a material.

**Conclusion:**

In the creep test, the type of stress applied to the specimen is uniaxial tension. This allows for the controlled measurement of the time-dependent deformation of the material under a constant tensile load. The use of uniaxial tension simplifies the test setup and analysis, making it a common and practical choice for studying creep behavior.