Select the statement that best summarizes the central idea of the article.

Electromagnets are useful in many situations because they can be turned on and off.
Motors change mechanical energy to electrical energy.
Electromagnets work whether or not electricity is passing through the wire.
Electromagnets are useful around the home but not in industry.

he uptake of drugs from the intestine is often strongly influenced by diffusion. for example, consider a water-insoluble steroid for treating inflammation that is solubilized in aggregates of detergent molecules, called micelles. these micelles, aggregates of 80 soap molecules, have a molecular weight of 24,000, a diameter of 2.6 nm, and a charge of -27. the positively charge ions (counterions) in this system are na".