In the following question, some part of the sentence may have errors. Find out which part of the sentence has an error and select the appropriate option. If a sentence is free from error, select 'No Error'.
Today the cost of living(A)/is so high that many people(B)/find it difficult to make ends meet.(C)/No error(D)
A Sonar of a ship sends sounds waves of speed 1500 m/s. These waves are reflected back by the ocean floor in 5 seconds. Find the depth (in m) of the ocean floor.