To answer this question we need to understand two parts one is what is abstract data type and another is what are the factors which makes one of the option as generalized queue ADT.
Abstract Data Type: ADT is a mathematical model of a data structure which contains a set of its instances, with: a specific interface - a collection of signatures of methods that can be invoked on an instance, a set of axioms that define the semantics of the methods.
Now coming to the Queue, a queue is a collection items which are kept in in such a order that addition of entities are done to the rear position, known as enqueue, and removal of entities from the front position, known as dequeue which makes the queue a First-In-First-Out (FIFO) data structure.
Now if we apply the above two definitions then single ended queue will satisfy this criteria.
