Thank you; that is precise.
I reread the two practice test questions you posted. The knowledge being tested appears to be that the IEEE 802.11 maxMSDU (message passing between LLC and MAC sub-layers) is 2304 octets -- regardless of what may happen to the data unit as it is processed by the MAC sub-layer.
The explanations of overhead for various cipher suites are extra information (that you might want to remember for other questions) but not essential to explain each question and its correct answer.
To ask that the explanations include the TKIP fragmentation quirk is a bit much, in my opinion. Expect that explanation to follow a question designed to test that knowledge.
I hope this helps. Thanks. /criss