How to create a custom MCQ with multiple selection using 3tries.

You can get the built-in functionality of a Multiple Response question slide by converting your slide to a Freeform Pick Many slide. 

The Convert to Freeform Slide button is on the Insert ribbon:

Clicking that button opens a window for choosing the type of question you want. For yours, you would select the Pick Many option.

After you choose the question type and click OK, Storyline converts the slide and switches it FORM VIEW. 

• In the Attempts field, indicate how many tries the user should get.
• In the Choice column, select the objects that are possible answers.
• In the Correct column, indicate which objects are correct. 

When you convert a slide to a Freeform question, Storyline automatically adds the built-in functionality that a standard graded question has.

• Storyline adds Correct and Incorrect layers. And when you adjust the Attempts to more than 1, it automatically adds a Try Again layer. 
  • Your slide already has those layers. So you can simply delete the layers that the program adds. Storyline will use your layers, because they have the exact same names.
  • You need to delete the "Jump to next slide" trigger from the Continue button on your Try Again layer. 

• Storyline adds a Submit button with the appropriate Submit__ trigger.
  • To use your on-slide Submit button, copy Storyline's default Submit__ trigger and paste it to your button.
  • To delete the built-in Submit button, deselect it from the Slide Properties (Slide Properties in Storyline 360 - E-Learning Heroes (articulate.com) ).

• • Storyline will automatically show the Prev and Next buttons in the Player when a user revisits the slide. If you don't want those buttons to show in the Player, do this:  Deselect the "Enable player navigation" checkbox in the Slide Properties (https://access.articulate.com/support/article/Storyline-360-Disable-Player-Navigation-When-Revisiting-Quiz-Questions ).
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  • If the slide is associated with a Results slide, Storyline will automatically reset the question if the Retry Quiz function is used.

Here's more information about Freeforms: https://community.articulate.com/series/articulate-storyline-360/articles/articulate-storyline-360-user-guide-how-to-convert-existing-slide-to-freeform-interaction

Thank You mam! Greatful for your help!!