The textbook exercise provides a list of words: कृषक, सैनिक, शिक्षक, चिकित्सक, and वैज्ञानिक. The sentence 'शिक्षा देने वाले' describes the function of a teacher. In Hindi, 'शिक्षा देना' means to give education, and the person who does this is called a 'शिक्षक' (Teacher). Therefore, the correct word to fill the blank is 'शिक्षक'.