TASK DEFINITION: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
PROBLEM: Passage: Towering in the Bielsko-Biała city centre, the Castle is the oldest and largest construction of historical importance, erected in the old town of Bielsko. A legend says that in its place there used to be a settlement of robbers who attacked travelling merchants. The Opolski Prince, Casimir (1229/30) of the Piasts is said to have conquered that fortalice, wiped out the robbers and had the hunting palace erected in that place, which over the years grew into a magnificent castle around which the city of Bielsko developed. The oldest part of the Castle dates back to 14th century. Over the next centuries the Castle gradually developed and transformed. It is a city castle in its nature, incorporated into the system of Bielsko fortifications from the beginning, at the same time providing their strongest section. Over the centuries it performed the function of a Silesian border-stronghold, first guarding the borders of Cieszyn and Oświęcim district duchies and then in the second half of the 15th century it protected the Czech and Polish state border and from 1526 - the Austrian-Polish border. Starting from the close of the 16th century, its defensive role was declining and the Castle gradually transformed into a nobleman’s mansion. The present appearance of the castle dates back to the last, thorough reconstruction undertaken in the second half of the 19th century, which entirely wiped out its previous characteristics of style. During the years 1899-1973, in place of brick breast wall presently seen on the east part of the Castle, there used to be a parade of bazaars, constituting an attractive architectural foundation for the body of the Castle. The bazaars were pulled down in connection with widening of Zamkowa Street. The Castle erected by Piasts ruling over the Cieszyn Dutchy was one of their residences for over two centuries. From 1572 it was the administrative and commercial centre of the independent class-based Bielsko state, governed by representatives of nobleman’s families of the Promnitzes, Schaffgotsches, Sunneghs, Solmses and Haugwitzes. In 1752, the position of that state was raised to the position of duchies which went into the rule of the Sułkowskis family. The Bielsko Dutchy existed until 1849, when Austria introduced modern administrative division, thus doing away with old feudal structures and was incorporated into Bielsko District Starosty. The Castle itself and numerous estates in the vicinity of the city remained in the possession of the Sułkowskis until 1945. After World War II the Castle was taken over by the Polish State as the property left by the Germans and was facilitated as the seat of many cultural institutions. Since 1983 the Castle sole usufructary has been the national Museum in Bielsko-Biała, subordinated to Silesian local government in Katowice.
 Link Information: The Piast dynasty was the first historical ruling dynasty of Poland. Answer: Poland

SOLUTION: Which country was Casimir from when he took the Bielsko-Biała Castle?

PROBLEM: Passage: Ward Thomas joined RAF Bomber Command in 1941 and trained as a navigator and pilot in South Africa. He joined 100 Squadron as a Lancaster pilot and was later moved to 550 Squadron stationed in Grimsby. He flew 36 trips over France and Germany over the course of the war, including taking part in the Nuremberg raid of March 1944 during which Bomber Command suffered its heaviest loses. He was awarded the Croix de Guerre for his involvement in bombing raids on the German Panzer training camp at Mailly-le-Camp in advance of the Normandy landings in June 1944. He also received the DFC "for utmost fortitude, courage and devotion to duty in air operations" during the War. By the time he left the RAF Ward Thomas had achieved the rank of flight lieutenant.
 Link Information: The Avro Lancaster is a British four-engined Second World War heavy bomber. Answer: Avro 

SOLUTION: Who was the manufacturer of the planes Thomas flew when he joined 100 Squadron?

PROBLEM: Passage: John Silvester, the Recorder of London referenced the spectre of Napoleon Bonaparte and the burgeoning Napoleonic Wars in his announcement of Perring's appointment, stating that "At a time so awful as the present, when the country is threatened by an implacable and unprincipled enemy, it is of the last importance that the civic chair should be filled by a person in whom the greatest confidence can be placed". Silvester ominously warned Perring that "The keys of the Metropolis are placed in your hands, at the moment when the enemy are at the gates". The ball held later that day at Guildhall was opened with a minuet danced by Perring's eldest daughter and the Spanish Ambassador. The Napoleonic wars and the threat of a French invasion had led to coastal batteries being built as fortifications along the south coast of England in the summer of 1803. Perring was furious to find that a battery had been built on land that he owned at the mouth of the River Yealm in Devon, and wrote to the Secretary of War, Lord Hobart. Perring was eventually pacified by many letters from John Graves Simcoe, who was in charge of the construction of the defences. With the threat of invasion by the French still present, Perring presented the colours of the Corporation of London to the ten regiments of the London Loyal Infantry who assembled at Blackheath on 18 May 1804. Perring was accompanied on the grand procession to Blackheath by the Earl of Harrington, Earl Amherst and Prince Frederick, Duke of York.
 Link Information: The Yealm is a river in Devon in England that rises 1,411 feet above sea level on the Stall Moor mires of south Dartmoor and travels 12 mi to the sea Answer: 12 mi

SOLUTION:
How long is the river in Devon where Perring owned land at the mouth of the river?