Betty made a simple electromagnet using just a battery and a wire. What could Betty do to increase the strength of her electromagnet? options:

Coil the wire around a test tube.

Coil the wire around a toothbrush

Coil the wire around a paper towel roll.

Coil the wire around a nail.

Many organizations release indexes used to measure the development of the world's countries. as we learned in this lesson, these indexes measure many factors, from life expectancy to happiness. in your opinion, what are the three most important factors we can use to determine how developed a country might be? explain your answers in a few sentences.