Answer: Option C. -> His boss is impressed at his performance
Answer: (c)

Answer: Option C. -> will discuss the growing population problem at the conference.
Answer: (c)The growing population problem will be discussed at the conference.They/Some people (a) discusses the growing population at the conference. (Tense has changed) (b) discussed the growing population al the conference. (Tense has changed) (c) will discuss the growing population problem at the conference. (correct) (d) discuss the growing population at the conference. (Tense has changed)

Answer: Option B. -> We have been surprised at the news.
Answer: (b)The news has surprised us. (a) We have surprised the news. (Meaning of sentence changed) (b) We have been surprised at the news. (Correct) (c) We had been surprised at the news. (Tense has changed) (d) We have been surprised with the news.(Incorrect preposition)

Answer: Option B. -> A massive tribal welfare programme has been launched by the government in Jharkhand.
Answer: (b)

Answer: Option A. -> The sky has been overcast by thick clouds.
Answer: (a)Thick clouds have overcast the sky. (a) The sky has been overcast by thick clouds. (Correct) (b) The sky overcast by thick clouds. (Helping verb is missing) (c) The sky is overcast by thick clouds. (Tense has changed) (d) The sky is being overcast by thick clouds. (Tense has changed)

Answer: Option A. -> It will never be forgotten by him.
Answer: (a)He will never forget it. (a) It will never be forgotten by him. (Correct) (b) It can never be forgotten by him. (Incorrect word/s) (c) It should never be forgotten by him. (Incorrect word/s) (d) It may never be forgotten by him. (Incorrect word/s)

Answer: Option A. -> Was an excursion to mountains planned by him?
Answer: (a)Did he plan an excursion to mountains? (a) Was an excursion to mountains planned by him? (Correct) (b) Had an excursion to mountains planned by him? (Tense has changed) (c) Is an excursion to mountains planned by him? (Tense has changed) (d) Has an excursion to mountains planned by him? (Tense has changed)

Answer: Option B. -> By whom are you taught English?
Answer: (b)Who teaches you English? (a) By whom English is taught to you? (Incorrect structure) (b) By whom are you taught English? (Correct) (c) By whom was you taught English? (Tense has changed) (d) By whom you are taught English? (Incorrect structure)

Answer: Option D. -> Cricket was being played by the boys.
Answer: (d)

Answer: Option A. -> Students who wished to clear SSC CGL widely use test series and study material of Pinnacle
Answer: (a)Test Series and study material of Pinnacle are widely used by students who wish to clear SSC CGL. (a) Students who wish to clear SSC CGL widely use test series and study material of Pinnacle.(Correct) (b) Students clearing exams widely use test series and study material of Pinnacle (Incorrectsubject) (c) Students who clear exams widely use test series of Pinnacle.(Incomplete information) (d) Students who wish to clear exams widely test series and study material of Pinnacle (Incorrectstructure)