Plurals

Hi, ..

In the following sentence,

All study subjects behaved the same, even when the test parameters were modified

can you please tell me whether it is:

- comparing the different subjects to one another such that, for example, subjects a and b behaved the same, even when the test parameters were altered, or

- referring to each one individually, irrelative of the other ones, such that a subject a behaved the same, even when the test parameters were altered, and that includes all other subjects.. ?

Thank you.