The answer is: (a), (b), (c), as seen in an mpeg video by clicking your mouse on the photograph below.
There is a pressure loss along the tube in any situation in which a fluid is flowing, for example, water in a city water distribution system or air in a tube as in this problem.
This effect is VERY small: it is barely visible using a tube like the one in the photograph. To enhance the effect, a glass stirring rod was inserted into the air flow tube to make its effective diameter smaller.
