Choose the word that best completes the following sentence. a star has ; it appears to be moving across the sky as a night progresses.
(a)-apparent motion
(b)-endless motion
(c)-excess energy
(d)-mass

Apparent motion

Explanation:

The stars rise in the east, move in the sky in the west direction until it reaches its highest point in the sky, from here they descend until they hide in the west. This apparent change of position of a star in the sky is called apparent motion,  this is a consequence of the Earth's rotation, which makes us believe that in appearance a star or a constellation has shifted in the sky throughout the night.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.