The slack exists, of course, because people continue to save even when the private sector demand for loans ebbs away. And they tend to save more, not...

The slack exists, of course, because people continue to save even when the private sector demand for loans ebbs away. And they tend to save more, not less, in scary times." The phenomenon referred to in the second sentence acts as

a) a destabilizer b) an automatic stabilizer

c) a consumption booster d) a crowding out mechanism