The correct answer is (b) Hammerbeam roof
To explain I would say: The hammerbeam roof was the culmination of the development of the arch-braced truss, allowing greater spaces to be spanned. The hammerbeam roof of Westminster Hall in London, designed by Hugh Herland and installed between 1395 and 1399, was the largest timber-roofed space in medieval Europe, spanning a distance of just over 20 metres (66 ft). It is considered to be the best example of a hammer-beam truss in England.
Hammer beam trusses can have a single hammerbeam or multiple hammerbeams. A false hammerbeam roof (truss) has two definitions: 1) There is no hammer post on the hammer beam as sometimes found in a type of arch brace truss or; 2)The hammer beam joins into the hammer post instead of the hammer post landing on the hammer beam.
