જો $BCOP$ $-30 \, mm \, Hg$ હોય,$CHP$ $-20 \, mm \, Hg$ હોય અને $GHP$ $+70 \, mm \, Hg$ હોય,તો $EFP$ શું હશે?

• A
  $+20 \, mm \, Hg$
• B
  $+30 \, mm \, Hg$
• C
  $+60 \, mm \, Hg$
• D
  $+120 \, mm \, Hg$