Read the text and determine if the sentence is true (see options at the end):

Measure<br>John wanted to know how dogs could find electronic devices. He set up a test to measure the chemicals off-gassed by plastic. John used a sensitive device that could detect odors. He found plastic devices gave off a certain chemical as they decayed. John published his research in an esteemed science journal.

Sentence: John used stray dogs for his tests
Available choices: (1). Yes; (2). It's impossible to say; (3). No;
(2).