Select the most appropriate option to fill blank 1.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. has been.
Explanation: The sentence is discussing progress over the last decades, indicating that progress has occurred in the past. Therefore, the verb tense used here should be the present perfect tense, which is "has been." This tense is used to describe actions or events that started in the past and have relevance to the present moment.
So, the sentence is emphasizing that progress has been made in the past, which is why "has been" is the appropriate choice for the first blank.