Sylius\Behat\Page\Admin\Promotion\CreatePageInterface::selectRuleOption PHP Method

    public function selectRuleOption($option, $value, $multiple = false);

 /**
  * @Given I add the "Total price of items from taxon" rule configured with :count :taxonName
  */
 public function iAddTheRuleConfiguredWith($count, $taxonName)
 {
     $this->createPage->addRule('Total price of items from taxon');
     $this->createPage->selectRuleOption('Taxon', $taxonName);
     $this->createPage->fillRuleOption('Amount', $count);
 }