question_answer

Direction: Read the passage carefully and answer the following questions. Three specimens of magnetic material were tested using the apparatus shown in the diagram. When the switch is closed, the specimen picks up some of the iron nails but when the switch is opened, many or most of the nails fall off. The number of nails picked up and left on were found for three specimens. The table shows the results.          

Specimen	Number of nails picked up	Number of nails retained by the specimen
X	35	4
Y	20	10
Z	40	3

Which material is the best electromagnet among the three?

A) X                                 

B) Y                     

C)        Z                     

D)        All of these.