Could anyone help me rearrange my code so that mousepressed presses all four ellipses?

The assignment is to create four ellipses that each have a different sound, and to make the code run so that each ellipse plays its sound when clicked (mousepressed). I have managed to get the top two ellipses to work; however, I cannot get the other two to work so I would really appreciate some help. (Down at the very end with my if/else if/else statements).

    // import Minim
     import ddf.minim.*;

     Minim minim;
     AudioSample d1;
     AudioSample d2;
     AudioSample d3;
     AudioSample d4;

     AudioOutput out;

     // track when a drum has been struck
     boolean drum1struck;
     boolean drum2struck;
     boolean drum3struck;
     boolean drum4struck;


     void setup() {
       // initialize the screen
       size(400, 400);
       smooth();

       // initialize sound
       minim = new Minim(this);
     out = minim.getLineOut();

       d1 = minim.loadSample("bongo1.wav");
       d2 = minim.loadSample("bongo7.wav");
       d3 = minim.loadSample("tom1.wav");
       d4 = minim.loadSample("tom2.wav");

       // set boolean variables to initialize the graphics
       drum1struck = false;
       drum2struck = false;
       drum3struck = false;
       drum4struck = false;

     }

     void draw() {
        background(255);

       // draw the drums: if a drum has just been struck
       // then fill its ellipse with color as visual feedback for the user

       // drum 1
       if (drum1struck == true) {
         fill(255,0,0);
         drum1struck = false;
       }
       else
       {
         fill(255);
       }
       ellipse(50, 55, 100, 100);

       // drum 2
       if (drum2struck == true) {
         fill(255,0,0);
         drum2struck = false;
       } else {
         fill(255);
       }
       ellipse(160, 55, 100, 100);

       //drum 3
       if (drum3struck == true) {
         fill(255,0,0);
         drum3struck = false;
       }
       else {
         fill(255);
       }
       ellipse(50, 165, 100, 100);

       //drum 4
       if (drum4struck == true) {
         fill(255,0,0);
         drum4struck = false;
       } else {
         fill(255);
       }
       ellipse(160, 165, 100, 100);


     }
     void keyPressed() {
       if (key == 'a' || key == 'A') {   //note you may have to retype the
         drum1struck = true;             //single quote marks after copying
         d1.trigger();
       }
       else if (key == 'b' || key == 'B') {
         drum2struck = true;
         d2.trigger();
       }
       else if (key == 'c' || key == 'C') {
         drum3struck = true;
         d3.trigger();
       }
       else if (key == 'd' || key == 'D') {
         drum4struck = true;
         d4.trigger();
       }
     }

     void mousePressed() {
       if (mouseX<105)
       {
            d1.trigger();
            //set Boolean for drum1 to true
            drum1struck = true;
       }
       else if (mouseX>105)
            {d2.trigger();
            //set Boolean for drum1 to true
           drum2struck = true;
       }
      else if (mouseY<-200)
       {
            d3.trigger();
            //set Boolean for drum1 to true
            drum3struck = true;
       }
       else  {
            d4.trigger();
            //set Boolean for drum1 to true
            drum4struck = true;
     }
     }