In view of the fact that his enemies knew him as cheerful, his allies exhorted him, as a matter of self-preservation, to ------- himself as taciturn.（）

A．impinged on their writing's vividness
B．contaminated their writing' s impartiality
C．undermined their writing's narrative coherence
D．restricted their writing's resonance
E．limited their writing' s perceptiveness

A．hypocrisy
B．indolence
C．refutation of findings
D．profusion
E．depletion