Hindustan Aeronautics Limited (HAL) has been developing its second supersonic light combat aircraft, Tejas, since 2003 from scratch for Indian Defence Force. The designing and manufacturing of an aircraft is a complex process. Moreover, the terrains guarded by the Indian Defence Force are also some of the most difficult ones in the world; this made the entire process even more complex. The designing, testing and initial production of the aircraft has completely been in conjunction with the Indian Air Force and the Indian Navy. After nearly a decade of testing by the defence forces and further improvements done by HAL, in February 2021, the Indian Air Force (IAF) was satisfied with the product to place an additional order for 83 Tejas aircraft with HAL. For nearly two decades, HAL was working very closely with the IAF and the Indian Navy. Which of the following strategies did HAL use for its Tejas aircraft? Make-to-stock (MTS) Assemble-to-order (ATO) Configure-to-order (CTO) Engineer-to-order (ETO)