Which of the following, on a standalone basis, could give rise to a range of outcomes in determining the time required to deliver a particular work package? 1. Including learning curves with a range of assumptions to approximate the possible time savings associated with repeated actions required to deliver the work package 2. A range of potential availability of scarce skilled resource needed to deliver the work package 3. Dependency on a preceding work package that itself has a range of possible outcomes 4. Uncertainty of scope of the work package that will only be resolved once work is underway 1 only 2 & 3 4 only 1.2 & 4