Responsibilities of a class are derived from .
a) behavioral models of the to-be system
b) interviewing nouns in the use case description
c) verbs in the use case description

The correct option is a behavioural models of the the to-be system.

Explanation:

As the  Use case analysis method generates the analysis classes list  such that the classes are capable of performing the behavior needed to make the system function successfully. From these analysis classes list the responsibilities of each class are defined.

As the list is derived from the behavioural models of the system, thus option a is the correct option.

it would be kevlar ^^

he made 11 calls in one day