Which of the following is most responsible for el niño?

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

Legumes, a type of plant, require rhizobia, a type of soil bacteria, to survive since these organisms fix nitrogen during photosynthesis. rhizobia use the legumes for food. what would most likely happen to the legume population if rhizobia suddenly became extinct?

The activity of the modern sample is 1.10 bq . how long does that measurement take?