An Estimating using Risk Analysis (ERA) has been performed on the above project (Proposed Bus Layby at Hiram's Highway) and the estimated total value for the risk of the proposed contract calculated by ERA is x%. It is noted that the value of the works with firm quantities is approximately 75% of the estimated value of the works excluding provisional and contingency sums. Discuss the two-step approach to be adopted in choosing the main option following the Guidelines of the Practice Notes for NE