SPOT THE ERRORSBut to see boys by dozen(A) take jobs lasting from six o'clock in the evening(B) till two in the morning(C) is a heartrending spectacle. (D)

Explanation

The sentence should read: "But to see boys by the dozen take jobs lasting from six o'clock in the evening till two in the morning is a heartrending spectacle."The error in the original sentence is the absence of the definite article "the" before "dozen". The correct idiomatic expression is "by the dozen", which means in large numbers or quantities.