How are electromagnets temporary? A.) They are only magnetic when an electric current runs through them.
B.) They are only magnetic when a gravitational wave runs through them.
C.) They are only magnetic when near a lodestone.
D.) They are only magnetic for two weeks.

Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a differential and enrichment culture.