Here, the answer is A.
7 tenths is 7 over 10, if you divide 7 by 10 you get 7 tenths as a decimal which is 0.7
Similarly, 45 tenths is 45 over 10,if you divide 45 by 10 you get 45 tenths as a decimal which is 4.50
21 hundredths is 21 over 100, if you divide 21 by 100 you get 21 hundredths as a decimal which is 0.21
Hence, the sum of 7 tenths, 21 hundredths and 45 tenths is (0.7 + 0.21 + 4.50) = 5.41