Passage: In June 2009, the Indian Air Force (IAF) selected the C-17 for its Very Heavy Lift Transport Aircraft requirement to replace several types of transport aircraft. In January 2010, India requested 10 C-17s through the U.S.s Foreign Military Sales program, the sale was approved by Congress in June 2010. On 23 June 2010, the Indian Air Force successfully test-landed a USAF C-17 at the Gaggal Airport to complete the IAFs C-17 trials. In February 2011, the IAF and Boeing agreed terms for the order of 10 C-17s with an option for six more; the US$4.1 billion order was approved by the Indian Cabinet Committee on Security on 6 June 2011. Deliveries began in June 2013 and were to continue to 2014. In 2012, the IAF reportedly finalized plans to buy six more C-17s in its Five-Year plans of India for 2017-2022.  However, this option is no longer available since C-17 production ended in 2015.
How many C-17s could Beoing order in February 2011 total?