This contract type may be used only when-

1. (a) The work required cannot otherwise be clearly defined;

2. (b) The required level of effort is identified and agreed upon in advance;

3. (c) There is reasonable assurance that the intended result cannot be achieved by expending less than the stipulated effort; and

4. (d) The contract price is the simplified acquisition threshold or less, unless approved by the chief of the contracting office.