Which statement best describes a valid scientific claim? The results of the experiment can be replicated by using any method of experimentation.
The results that support the claim are replicable by other scientists who follow the same procedures.
The claim is jointly issued from both a major university and an established government agency.
The claim is supported by at least ten scientists in addition to the original researcher.

i think the answer is b.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms