Task: Question Generation
Input (English): Passage: The existence of 400 churches has been recorded throughout the kingdom; most have yet to be located. Only seven have been identified so far, given the simple names of church "A", "B", "C", "E", the "Mound C" church in Soba, the church in Saqadi and the temple-church in Musawwarat as-Sufra. Churches "A"–"C" as well as the "Mound C" church were basilicas comparable to the largest Makurian churches. The Saqadi church was an insertion into a pre-existing structure. Church "E" and the church of Musawwarat es-Sufra were "normal" churches. Thus, the known Alodian houses of worship can be categorized into three classes.
On "Mound B" in Soba lay the standalone complex of the three churches "A", "B" and "C". Churches "A" and "B", both probably built in the mid-9th century, were large buildings, the first measuring 28 m × 24.5 m (92 ft × 80 ft) and the second 27 m × 22.5 m (89 ft × 74 ft). Church "C" was much smaller  and built after the other two churches, probably after c. 900. The three churches had many similarities, including having a narthex, wide entrances on the main east-west axis and a pulpit along the north side of the nave. Differences are evident in the thickness of the bricks used. Church "C" lacked outer aisles. It seems probable that the complex was the ecclesiastical center of Soba, if not the entire kingdom.
Church "E", on a natural mount, was 16.4 m × 10.6 m (54 ft × 35 ft) in size (and like all red brick structures in Soba heavily robbed). Its layout was unusual, such as its L-shaped narthex. The roof was supported by wooden beams resting on stone pedestals. The internal walls used to be covered by painted whitewashed mud; the external walls were rendered in white lime mortar.The "Mound C" church, perhaps the oldest of the churches of Soba, was around 13.5 m (44 ft) in length. It was the only Alodian church known to have incorporated stone columns. Very little remains of it and its walls, probably made of red bricks, have completely disappeared. Five capitals have been noted, belonging to a style that appeared in Nubia at the turn of the 8th century.
Output (English): Which church incorporated stone columns?