The <e1>rainbows</e1> are caused by the <e2>refraction</e2>, or bending, of sunlight as it passes through the raindrops.
The rainbows are caused
The rainbows are caused by the refraction, or bending, of sunlight as it passes through the raindrops.
<triplet> rainbows <subject> refraction <object> Cause-Effect(e2,e1)