Correct Answer:
Option D - Past Perfect Continuous tense has the following form subject + had + been + verb (continuous form). So 'had been playing' is the correct option. Hence sentence will be 'The boys are playing cricket' will be 'The boys had been playing cricket'.
D. Past Perfect Continuous tense has the following form subject + had + been + verb (continuous form). So 'had been playing' is the correct option. Hence sentence will be 'The boys are playing cricket' will be 'The boys had been playing cricket'.