Architects of Romanesque churches began installing ________ around the apse, which allowed the overflow of pilgrims to circulate freely around the interior of the church

A. scaffolding
B. ambulatories
C. underground walkways
D. transepts
E. barrel vaulting

B
Due to the large crowds of pilgrims visiting Romanesque churches, ambulatories were designed to allow circulation around the apse, without disturbing devotions in progress.