Final answer:
The idea promoted by the poster is that women can do the same jobs as men. Therefore, the correct option is A.
Step-by-step explanation:
The idea promoted by the poster is A) Women can do the same jobs as men. The image depicts a woman using a drill machine to do a job typically associated with men, implying that women are capable of performing the same work. The words on the poster, 'Do the job he left behind,' further reinforce the notion that women are capable of taking on the tasks left by men.