Check only one ToolStripMenuItem

I have a ToolStrip with multiple ToolStripDropDownButtons, each has a set of DropDownItems.

When the user clicks on an DropDownItem, the check mark is shown.

By default, multiple items can be clicked and therefore multiple check marks appear.

What I'm trying to do is when the user clicks one DropDownItem, the other already checked items should be unchecked. In other words, there should always be only one checked item in the DropDown list.

I've been dabbling with it for some time but I can't really figure out how to keep the current checked item as it is while uncheck other items.

Below is the code I have as of now.

private void subietm1ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            UncheckOtherToolStripMenuItems(sender);
        }

        public void UncheckOtherToolStripMenuItems(object selectedMenuItem)
        {
            List<ToolStripDropDownButton> dropdownButtons = new List<ToolStripDropDownButton>();
            foreach (ToolStripItem item in toolStrip1.Items)
            {
                if (item is ToolStripDropDownButton)
                {
                    dropdownButtons.Add((ToolStripDropDownButton)item);
                }
            }

            foreach (ToolStripDropDownButton btn in dropdownButtons)
            {
                foreach (ToolStripMenuItem d in btn.DropDownItems)
                {
                    if (d.Checked)
                        d.CheckState = CheckState.Unchecked;
                }
            }
        }

If someone could shed some light on this or tell me an easy way to go about it, I'd be grateful.

Thank you.

So easy...

Implement their method as described below:

    private void subietm1ToolStripMenuItem_Click(object sender, EventArgs e)
    {
        UncheckOtherToolStripMenuItems((ToolStripMenuItem)sender);
    }

    public void UncheckOtherToolStripMenuItems(ToolStripMenuItem selectedMenuItem)
    {
        selectedMenuItem.Checked = true;

        // Select the other MenuItens from the ParentMenu(OwnerItens) and unchecked this,
        // The current Linq Expression verify if the item is a real ToolStripMenuItem
        // and if the item is a another ToolStripMenuItem to uncheck this.
        foreach (var ltoolStripMenuItem in (from object 
                                                item in selectedMenuItem.Owner.Items 
                                            let ltoolStripMenuItem = item as ToolStripMenuItem 
                                            where ltoolStripMenuItem != null 
                                            where !item.Equals(selectedMenuItem) 
                                            select ltoolStripMenuItem))
            (ltoolStripMenuItem).Checked = false;

        // This line is optional, for show the mainMenu after click
        selectedMenuItem.Owner.Show();
    }

One detail is that you can implement the same method for all click menuItens, for this add same call for method UncheckOtherToolStripMenuItems((ToolStripMenuItem)sender); into the Event click for each ToolstripMenuItem, see this example to the another two ToolstripMenuItens:

    private void subietm2ToolStripMenuItem_Click(object sender, EventArgs e)
    {
        UncheckOtherToolStripMenuItems((ToolStripMenuItem)sender);
    }

    private void subietm3ToolStripMenuItem_Click(object sender, EventArgs e)
    {
        UncheckOtherToolStripMenuItems((ToolStripMenuItem)sender);
    }