Question: which German 88 mm anti-aircraft and anti-tank artillery  was produced by  Spreewerk 

Context paragraphs:
Mikhail Feofanovich Potapov: Mikhail Feofanovich Potapov (Russian: Михаи́л Феофа́нович Пота́пов , 23 January 1921 - 8 July 1943) was a Soviet Red Army artillery captain and commander of an anti-tank artillery battery from the 1188th Anti-Tank Artillery Regiment of the 13th Anti-Tank Artillery Brigade, 2nd Tank Army.  Potapov's battery destroyed ten German tanks near the Ponyri railway station at the Battle of Kursk.

8.8 cm Pak 43: The Pak 43 ("Panzerabwehrkanone 43" and "Panzerjägerkanone 43") was a German 88 mm anti-tank gun developed by Krupp in competition with the Rheinmetall 8.8 cm Flak 41 anti-aircraft gun and used during World War II.  The Pak 43 was the most powerful anti-tank gun of the Wehrmacht to see service in significant numbers, also serving in modified form as the 8.8 cm KwK 43 main gun on the Tiger II tank, to the open-top Nashorn, and fully enclosed, casemate-hulled Elefant and Jagdpanther tank destroyers.

45 mm anti-aircraft gun (21-K): The 45 mm anti-aircraft gun (21-K) was a Soviet design adapted from the 45 mm anti-tank gun M1932 (19-K).  This was a copy of a 3.7 cm German weapon designed by Rheinmetall that was sold to the Soviets before Hitler came to power in 1933 that had been enlarged to 45 mm to reuse a large stock of old 47mm ammunition.  It was used by the Soviet Navy to equip almost all of their ships from 1934 as its primary light anti-aircraft gun until replaced by the fully automatic 37 mm "70-K" gun from 1942 to 1943.  It was used in World War II and during the Cold War as the Soviets exported their World War II-era ships to their friends and allies.  However it was not very effective as its slow rate of fire and lack of a time fuze required a direct hit to damage targets.

QF 3.7-inch AA gun: The QF 3.7-inch AA was Britain's primary heavy anti-aircraft gun during World War II.  It was roughly the equivalent of the German 88 mm FlaK and American 90 mm, but with a slightly larger calibre of 94 mm.  It was used throughout World War II in all theatres except the Eastern Front.  The gun was produced in six major variants, two versions (mobile and fixed) and in considerable numbers.  The Mk VI ordnance used only with a fixed mounting gave vastly increased performance.  It remained in use after the war until AA guns were replaced by guided missiles, notably the Thunderbird, in the late 1950s.  The gun was also used as the basis for the Ordnance QF 32-pounder anti-tank gun variant used on the Tortoise heavy assault tank.

105mm Gun T8: 105mm Gun T8 was an anti-tank gun developed in the United States in mid-1940s.  This gun's design was influenced by German 88 mm Pak 43/41 anti-tank guns captured by the U.S. Army in France.  The development started in October 1944; the gun reached trials in February 1946.  Soon afterwards the project was cancelled.

Spreewerk: Metallwarenfabrik Spreewerk GmbH was a German weapons manufacturing company.  Spreewerk produced a number of important weapons and components before and during World War II including 280,880 of the Walther P.38 pistol which was the standard service pistol of the German "Heer", and the famous 8.8 cm Flak anti-aircraft gun.

Commander, Royal Artillery: Commander, Royal Artillery (abbreviated CRA) was a military appointment in Commonwealth infantry and armoured divisions in the 20th century.  The CRA was the senior artillery officer in the division and commanded the regiments of field, anti-aircraft and anti-tank artillery, and provided specialist artillery and offensive support advice to the divisional commander.  Even though the Canadians, New Zealanders, etc. had their own artillery corps (i.e. the Royal Regiment of Canadian Artillery), the term CRA was still used to mark this appointment in formations of those armies (rather than CRCA or CRNZA etc.) for consistency between the allies.  The CRA was usually ranked as a brigadier-general in the First World War, and as a brigadier in the Second World War, and if he held this rank was usually referred to as the Brigadier-General, Royal Artillery (BGRA) or Brigadier, Royal Artillery (BRA).

8.8 cm Flak 18/36/37/41: The 8.8 cm Flak 18/36/37/41 (commonly called the eighty-eight) was a German 88 mm anti-aircraft and anti-tank artillery gun from World War II.  It was widely used by Germany throughout the war, and was one of the most recognized German weapons of that conflict.  Development of the original model led to a wide variety of guns.

8.8 cm Flak 16: The 8.8 cm Flak 16 was a German 88 mm anti-aircraft artillery gun from World War I, the forerunner of the later 88 mm guns of World War II.  Its contemporary name was the 8.8 cm K.Zugflak L/45.

3.7 cm Flak 18/36/37/43: The 3.7 cm Flak 18/36/37/43 was a series of anti-aircraft cannon produced by Nazi Germany that saw widespread service in the Second World War.  The cannon was fully automatic and effective against aircraft flying at altitudes up to 4,200 m.  The cannon was produced in both towed and self-propelled versions.  Having a flexible doctrine, the Germans used their anti-aircraft pieces in ground support roles as well; 37 mm caliber guns were no exception to that.  With Germany's defeat, production ceased and, overall, 37 mm caliber anti-aircraft cannon fell into gradual disuse, being replaced by the Bofors 40 mm gun and later, by 35-mm anti-aircraft pieces produced in Switzerland.

Supporting paragraphs: Spreewerk 8.8 cm Flak 18/36/37/41
Answer: The 8.8 cm Flak