If in a certain code, '345' means 'you are good', '358' means 'good is nice' and '783' means 'nice and good', then which digit stands for 'is'? MCQ with Answer and Explanation

From first two, good =3 or 5. From second and third, good =3 or 8. Common good =3. Then from second, remaining for 'is' and 'nice' are 5 and 8. From third, nice and and are 7 and 8 (since good=3). Common for nice is 8. Thus from second, 'is' =5. Wait, then answer B. From above: second 358 = good is nice, good=3, so is and nice =5,8. Third 783 = nice and good, good=3, so nice and =7,8. Thus nice =8, then is =5, and =7. Yes, 'is' =5.