Answer:
P
Step-by-step explanation:
The SI prefixes nano- and pico- stand for ...
nano- = 10^-9
pico- = 10^-12
2500 picometers is 2500·10^-12 = 2.5·10^-9 = 2.5 nanometers.
25 nanometers is greater than 2.5 nanometers, so is the greater length. Organism P has the greater length.