Hi there,

So unfortunately, this is a very ambiguous question. In general, the relationship between temperature and velocity in a fluid is quite complicated, however we can think about the reasoning that the question maker was after.

First of all, there's nothing to indicate that this is a non-ideal fluid, so we can safely apply Bernoulli's equation. Since it's a horizontal pipe, the heights at the two points are the same, so that means if the velocity is greater at one point, then the pressure must be less there (this is the same reasoning behind lift forces on an airplane wing).

Now, recall that pressure is due to the impulse exerted on the walls by the individual molecules in the course of their random translational motion. Less pressure means less random motion which is what we associate with the temperature of a substance. Thus, we should expect a lower temperature (i.e. answer A).

You can also get this relationship from the ideal gas law (of course there's nothing suggesting this fluid is a gas):

PV=nRT,

which says that pressure is proportional to temperature (at fixed volume).

Hope this helps.