Correct answer only if you know
a scientist studying fossils in undisturbed layers of rock identified a species that appeared to have changed little over the years. which observation would have most likely led him to this conclusion?

a
the simplest fossil organisms appeared only in the newest rocks.

b
no fossil organisms of any kind appeared in the newest rocks.

c
the simplest fossil organisms appeared only in the oldest rocks.

d
the same kind of fossil organisms appeared in old and new rocks.

answer: although many types of viruses can cause a common cold, rhinoviruses are the most common culprit. a cold virus enters your body through your mouth, eyes or nose. the virus can spread through droplets in the air when someone who is sick coughs, sneezes or talks. theres your answer

explanation:

correct answer is a. and d.

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.