Final answer:
The measurement of Chlamydia trachomatis elementary bodies in nanometers is 250 nm.
Step-by-step explanation:
To convert micrometers (µm) to nanometers (nm), we need to multiply the measurement by 1000. Since the question states that the diameter of Chlamydia trachomatis elementary bodies is 0.25 micrometers, we can calculate the measurement in nanometers as follows:
0.25 µm * 1000 = 250 nm
Therefore, the measurement of Chlamydia trachomatis elementary bodies in nanometers is 250 nm.