$activityContacts = CRM_Core_OptionGroup::values('activity_contacts', FALSE, FALSE, FALSE, NULL, 'name');
$assigneeID = CRM_Utils_Array::key('Activity Assignees', $activityContacts);
$scheduledStatus = CRM_Core_OptionGroup::getValue('activity_status', 'Scheduled', 'name');
$activityContacts = CRM_Core_OptionGroup::values('activity_contacts', FALSE, FALSE, FALSE, NULL, 'name');
$assigneeID = CRM_Utils_Array::key('Activity Assignees', $activityContacts);
$scheduledStatus = CRM_Core_OptionGroup::getValue('activity_status', 'Scheduled', 'name');