IOrganizationService _service;

public void Execute(IServiceProvider serviceprovider)
        {
            IPluginExecutionContext context = (IPluginExecutionContext)serviceprovider.GetService(typeof(IPluginExecutionContext));
            IOrganizationServiceFactory servicefactory = (IOrganizationServiceFactory)serviceprovider.GetService(typeof(IOrganizationServiceFactory));
            IOrganizationService service = servicefactory.CreateOrganizationService(context.UserId);

            if (context.InputParameters.Contains("Target") && context.InputParameters["Target"] is Entity)
           {

                Entity ent = (Entity)context.InputParameters["Target"];

                if (ent.LogicalName != "opportunity")
                    return;

                string connstring = @"Url=https://mlptcare.crm5.dynamics.com; Username=Jaya@mlptcare.onmicrosoft.com; Password=CrmAdmin365; authtype=Office365";
                CrmServiceClient conn = new Microsoft.Xrm.Tooling.Connector.CrmServiceClient(connstring);
                service = (IOrganizationService)conn.OrganizationWebProxyClient != null ? (IOrganizationService)conn.OrganizationWebProxyClient :

(IOrganizationService)conn.OrganizationServiceProxy;


                try
                {
                    Guid fabercastel = new Guid("efd566dc-10ff-e511-80df-c4346bdcddc1");
                    Entity _account = new Entity("account");
                    _account = service.Retrieve(_account.LogicalName, fabercastel, new ColumnSet("name"));

                    string x = _account["name"].ToString();


                    throw new InvalidPluginExecutionException("Result of Query : " + x);
                }
                catch (Exception ex)
                {
                    throw new InvalidPluginExecutionException(ex.Message);
                }