Q: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Passage: The church is constructed in punch-dressed sandstone ashlar, and has slate roofs with inserted skylight windows. Its architectural style is Early English. The plan consists of a four-bay nave without aisles, a two-bay chancel with a north chapel and a south vestry, and a west tower. The tower is in three stages, with clasping buttresses, and contains paired west doorways, a clock face in a diamond-shaped surround, and pairs of louvred bell openings. At the top of the tower is an embattled parapet with octagonal corner pinnacles, and there are more pinnacles at the angles of the nave. The bays of the nave are separated by buttresses, and each bay contains a corbel-table and a pair of lancet windows. The sides of the chancel also contain paired lancet windows, and the east window consists of a triple stepped lancet in a blank arch. The north chapel is gabled, and contains a wheel window. The interior has been remodelled, but originally it contained a three-sided gallery on cast iron columns.
Link Information:

Early examples of buttresses are found on the Eanna Temple (ancient Uruk), dating to as early as the 4th millennium BCE. Question: In what century did the clasping architectural feature seen on the tower first begin to be used?
A:
Answer: 4th millennium BCE