*Net* thermal energy exchanged?

[Greg777]

Homework Statement

Hello, I have the following problem (an ABCD question):

Two objects near each other are at the same temperature. Which of the following statements has to be true?
A. The objects have the same internal energy.
B. The objects have the same thermal capacity.
C. No thermal energy is exchanged between the objects.
D. The net thermal energy exchanged between the objects is zero.

Homework Equations

I think there are none, it's rather conceptual.

The Attempt at a Solution

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I think there's nothing wrong with C but according to the markscheme the correct one is D. Well, I think that both C and D are correct. If C is wrong, if the objects are at the same temperature how may there be any exchange of thermal energy between them?

 

[mfb]

They both emit thermal radiation, for example. The net exchange is zero but there is a constant flow of energy in both directions.