The majority of the talk was devoted to an account of the experimental methods used by investigators in the field.
b. The greater part of the talk was
c. The bulk of the talk has been
d. A large amount of the talk has been
e. A predominance of the talk was
I will go with B
Talk is not countable so The majority of the talk is not correct. Majority is used for countables. For e.g. The student majority is....
C- The bulk of talks... awkard and again bulk is used for countables
D. Large is also used for numbers
E. A predominance of the talk.... how does that sound to the ear?