Answer:
B. Encouraging
Step-by-step explanation:
The tone used by PSA to effectively promote women joining the work force during World War II was encouraging.
PSA is an acronym for Public service announcement which is refer to as a message spread without charge and the main aim is to raise awareness to the public or geared towards changing the public view or behavior in respect of a social issue.
Though PSA has diverse names it is called in various countries, in Hong Kong, it is known as 'announcements in public interest' ('AIPs') while it is called 'public information films' ('PIFs') in the United kingdom.