Looks D to me
A) Catherine II of Russia was far more attentive to the state of the Russian Empire than her husband Peter III and planned
comparing actions here. Need verb after <than>.
B) The attentiveness of Catherine II of Russia to the state of the Russian Empire was far more than that of her husband Peter III, planning
misplaced modifier. what is palnning
C) The attentiveness of Catherine II of Russia to the state of the Russian Empire was far more than that of her husband Peter III, who planned
wronr meaning, restrictive clause modifing husband Peter but the clause's meaning is wrong..
D) Catherine II of Russia was far more attentive to the state of the Russian Empire than was her husband Peter and planned
was attentive and planned.. parallel .. Good choice.
E) Catherine II of Russia was attentive to the state of the Russian Empire, far more than her husband Peter III, planning
missing verb and again participle modifying what???