In this case, the correct answer is "unwinnable." Walter Cronkite, a prominent news anchor, started to express his opinion that the Vietnam War was "unwinnable." This perspective of a respected figure in the media caused the public to start questioning the war effort and its viability.
Here's why "unwinnable" is the most suitable option:
1. "Necessary" implies that the war was justified and essential, which doesn't align with Cronkite's assessment.
2. "Thoughtful" is a vague descriptor and doesn't capture the sentiment expressed by Cronkite regarding the war.
3. On the other hand, "unwinnable" accurately reflects Cronkite's view that the war was not progressing in a way that would lead to a clear victory, leading to doubts among the public.
Therefore, the most appropriate word from the given options that fits the context is "unwinnable."
