Answer:
D). The phrase “Handwashing is IN” means that it is in fashion for people to wash their hands.
Step-by-step explanation:
'Bandwagon technique' is illustrated as a persuasive technique or propaganda that is employed by the author to convince the audience/reader by presenting an idea that is followed and propagated by the majority. This persuades them emotionally to accept and agree with the idea or claim proposed.
As per the question, the poster best demonstrates the use of 'bandwagon technique' by the use of phrase 'Hand-washing is IN' as the word 'IN' is mentioned in capital letters to symbolize that the majority follows the(given) idea and it has become 'a fashion for people to wash their hands'. Thus, option D is the correct answer.