thE ExAmplE oF tEnnis is mEntionED in thE lAst pArAgrAph to suggEst thAt mEntAl ExErCisE ______.
A．CAn CountEr AgE-rElAtED mEntAl DEClinE in A ComprEhEnsivE wAy
B．oFFErs BEnEFits DirECtly BounD up with thAt kinD oF ExErCisE
C．shoulD BE pAirED with physiCAl ExErCisE For mAximum BEnEFit
D．is CompArABlE to physiCAl ACtivitiEs in tErm oF its importAnCE to ovErAll hEAlth