Question: The Airco DH.9 was named after which British aviation pioneer?

Context paragraphs:
Airco DH.9: The Airco DH.9 (from de Havilland 9) – also known after 1920 as the de Havilland DH.9 – was a British single-engined biplane bomber developed and deployed during the First World War.

De Havilland Oxford: The Airco DH.11 was a British twin-engined biplane bomber which was designed to replace the earlier Airco DH.10 bomber.  It was designed to use the unsuccessful ABC Dragonfly engine and was abandoned after the first prototype was built.

De Havilland DH.14 Okapi: The de Havilland DH.14 Okapi was a British two-seat day bomber of the 1910s built by de Havilland.  The aircraft was designed as an Airco DH.4 and DH.9 replacement, but it never entered production.

Geoffrey de Havilland: Captain Sir Geoffrey de Havilland (27 July 1882 – 21 May 1965) was a British aviation pioneer and aircraft engineer.  His Mosquito has been considered the most versatile warplane ever built, and his Comet was the first jet airliner to go into production.

British Aviation Services: British Aviation Services Limited (Britavia) was an early post-World War II airline holding company and air transport operator that could trace its roots back to 1946.  Its main activities included trooping, inclusive tour (IT) and worldwide passenger and freight charter services. British Aviation Services' first investment in a British independent airline occurred in 1946, when it acquired a minority interest in Silver City Airways.  Silver City Airways operated the world's first cross-Channel air ferry service on 13 July 1948.  It subsequently became British Aviation Services' biggest operating division.  In 1953, British Aviation Services took over the independent airline Air Kruise.  The same year, BAS Group also took control of Aquila Airways, the last commercial flying boat operator in the United Kingdom.  The completion of these acquisitions by mid-1954 resulted in a reorganisation of the British Aviation Services group, with British Aviation Services Ltd (BAS Group) becoming the group's holding company and Britavia one of its operating subsidiaries.  By the late 1950s, BAS Group became Britain's largest independent airline operator.  Its numerous operating divisions included Britavia's Hermes Division at Blackbushe Airport and Aquila Airways's Flying Boat Division at Hamble near Southampton.  The former concentrated on trooping services and inclusive tours while the latter provided scheduled services to Portugal, the Canary Islands and Italy.  In 1962, BAS Group merged with British United Airways (BUA), which by that time had replaced BAS as the UK's largest independent airline operator.

Airco DH.2: The Airco DH.2 was a single-seat biplane "pusher" aircraft which operated as a fighter during the First World War.  It was the second pusher design by Geoffrey de Havilland for Airco, based on his earlier DH.1 two-seater.  The DH.2 was the first effectively armed British single-seat fighter and enabled Royal Flying Corps (RFC) pilots to counter the "Fokker Scourge" that had given the Germans the advantage in the air in late 1915.  Until the British developed a synchronisation gear to match the German system, pushers such as the DH.2 and the F.E.2b carried the burden of fighting and escort duties.

Beardmore Halford Pullinger: Beardmore-Halford-Pullinger (BHP) were aircraft engines used in production between 1916 and 1918.  The engines were used on many notable First World War aircraft, such as the Airco DH.4, DH.9, DH.10, de Havilland DH.15 and Avro 529 aircraft.

Airco DH.9A: The Airco DH.9A was a British single-engined light bomber designed and first used shortly before the end of the First World War.  It was a development of the unsuccessful Airco DH.9 bomber, featuring a strengthened structure and, crucially, replacing the under-powered and unreliable inline 6-cylinder Siddeley Puma engine of the DH.9 with the American V-12 Liberty engine.

Airco DH.5: The Airco DH.5 was a British First World War single-seat fighter aircraft designed to replace the obsolete Airco DH.2.  It was one of the first British fighter designs to include the improved Constantinesco gun synchronizer, which allowed a forward-firing machine gun to fire through the propeller faster and more reliably than the older mechanical gears.  It was also one of the earliest biplanes to feature a marked "back-stagger" of its wings.  The DH.5 was inferior to other fighters already in production and proved unpopular and unsatisfactory in service.  It was replaced as soon as supplies of the S.E.5a permitted.

Airco DH.4: The Airco DH.4 was a British two-seat biplane day bomber of World War I.  It was designed by Geoffrey de Havilland (hence "DH") for Airco, and was the first British two-seat light day-bomber to have an effective defensive armament.  It first flew in August 1916 and entered service with the Royal Flying Corps (RFC) in March 1917.  The majority of DH.4s were actually built as general purpose two-seaters in the United States, for service with the American forces in France.

Supporting paragraphs: Airco DH.9 Geoffrey de Havilland
Answer: Captain Sir Geoffrey de Havilland