Answer:
Long term
Step-by-step explanation:
A business needs to plan in order to meet it business objectives and also to adequately satisfy the customer.
Short term plans are those that meet immediate business and customer needs. The require less preparation and cost to implement.
Long term plans require more planning and are meant to meet long term objective of the business. Cost is also higher than for short term plans.
In this scenario Boeing needs several years to develop an aircraft that has more fuel efficiency. So their plans are long term and aimed to satisfy customer needs.