A.
$("button").click(function(){ $(this).css("border","1px solid red") })
B.
$("button").click(function(){ $(this).css(border,1px solid red) })
C.
$("button").dbclick(function(){ $(this).css("border","1px solid red") })
D.
$("button").mouseover(function(){ $(this).css("border","1px solid red") })