What creates the magnetic field in an electromagnet?

a electric current through a straight piece of metal

b magnetic fields around a straight wire

c electric current through a wire coil

d all of these

Which best describes how the common cold spreads in the human body? a bacteria burst out of normal cells killing them b viruses replicate inside respiratory cells c bacteria inject dna into normal cells d viruses insert dna into bacteria

Explain how organisms could be harmed by high levels of salt from roadways?

Explain how scientists use geologic time to determine the age of landforms.