(A) Albania
(B) ** Bulgaria
EXPLANATIONS BELOW
Concept note-1: -The Incident at Petrich, or War of the Stray Dog, was a Greek–Bulgarian crisis in 1925 that resulted in a brief invasion of Bulgaria by Greece near the border town of Petrich after the killing of a Greek captain and a sentry by Bulgarian soldiers.
Concept note-2: -The border extends eastwards through the Nestos valley, up to the border tripoint between Greece, Bulgaria and Turkey, where it crosses the river called “Maritsa” by the Bulgarians and “Evros” by the Greeks. This border is in large part formed by the Rhodope mountain range.
Concept note-3: -Due to the strong political, cultural and religious ties between the two nations, (the majority of Bulgarians and Greeks practice the Eastern Orthodox faith), Bulgaria and Greece today enjoy excellent diplomatic relations and consider each other a friendly nation and an ally.