What is a flying buttress?
a. an architectural structure used to provide horizontal strength to a wall
b. a device used during the gothic period to build a large structure
c. a support system consisting of internal columns
d. none of the above

a. an architectural structure used to provide horizontal strength to a wall

Explanation:

The flying lobes were part against the side walls of the nave of the churches that aided its stability. And the buttresses were reinforcements that replaced the thick walls of the Romanesque buildings.

With the combined use of these support brackets, large openings in the walls became possible, and with that the stained glass windows gained prominence, an important element of Gothic architecture the stained glass windows provided illuminated, multicolored interiors that brought a feeling of lightness.

hi     (had to add 20 words)