1.pick off

a. the player responsible for the area between 2nd and 3rd base
b. the player on the mound in the middle of the field
c. the player positioned behind home plate
d. occurs when a fielder fails to make a play
e. a ball hit outside the 1st or 3rd base lines
f. a pitch thrown outside the strike zone
g. area over home plate between the armpits and the knees
h. a pitcher can throw three of these to get a batter out
i. the official behind home plate
j. when a pitcher throws out a base runner

The answer to the question is (d) occurs when a fielder fails to make a play.