The Popish Plot is an imaginary plot in which the death of Charles II were supposed to be planned by Roman Catholics and other government officers. 
Answer: D
Explanation 
The Popish Plot can be understood by marking the words from history - 'a unpleasant and hellish plot' (referred by the House of Commons) done by 'a shame to mankind' ( referred by Lord Justice Jeffreys to Titus Oates). 
The imaginary plot had Charles II to be executed and to replace the former with his brother James.