How can it be stated that Ralph's speech was highly appraised?

The choice that indicates Ralph's speech was highly appraised is phrased as "was considered to be." This wording effectively conveys a sense of evaluation and acknowledgment of quality. When something is "considered to be" of a certain standard, it suggests that it has undergone some form of assessment or judgment, which aligns perfectly with the idea of high appraisal.

On the other hand, the other options do not carry the same connotation of formal recognition or esteem. "Was expected to be" implies anticipation rather than evaluation, which does not capture the notion of appraisal. "Was said to be" merely reflects what people claimed without indicating any degree of approval, and "was thought to be" suggests an opinion but lacks the weight of a formal appraisal. Therefore, "was considered to be" is the most suitable choice to express that Ralph's speech received high praise.