Which of the following is true in twin - reversed - arterial perfusion (TRAP) sequence
TRAP sequence  is serious complication of monochorionic multifetal gestation. Donor twin has features of heart failure and recipient twin lacks heart.
It is caused by large artery-to-artery placental shunt.
It is caused by a large arteriovenous placental shunt.
Donor is at risk of cardiomegaly and high output heart failure.
Most effective treatment is injection of KCI into recipient twin.
Placental arterial perfusion pressure in the recipient exceeds that of the donor.