Question about COS 306 Computer Architecture Study.com Final assignment

[AllThose299s]

I'm still struggling with this assignment  :  Can't figure out the Control Unit, and now that I'm looking at the rubric, it says "Build the instruction selection unit using a multiplexer" which I think it's talking about the output of the operation blocks in the ALU and I did that, but the way it says "INSTRUCTION SELECTION UNIT" is confusing me as if they want a separate block for ISU just like they do for the control unit? 
I did the Final practice tests 16 times!!! Like 16 X 50 questions, and then last Saturday did the Final Exam and got 79 out of 100 (still pending proctor review). Worth to mention that literally not a single of the practice test questions were in the final exam!!!   Eventually I'm gonna transfer to WGU if I get enough points out of this assignment 
I'm drained and frustrated... Literally watched every single youtube video and tutorial and book on the internet but the way SDC assignment wants us to design the circuit is very different than all of the design processes I've seen from those tutorials and books! HELP!!!   

So what I noticed comparing some of the content from SDC vs some of the links on this forum is that SDC shows the example of using a multiplexer to control which gates are active (https://study.com/academy/lesson/buildin...gisim.html) but it's only using a single bit to control the multiplexer where some of the links on this forum shows examples of using a multiplexer in logisim with multiple bits. You are on the right path of what you are thinking what they are asking for on that part.

As for what they are asking in the Instruction Selection Unit, if you built the instruction selection unit using the multiplexer then you know what selection of bits in your multiplexer does what, but I don't so what they are asking for is to create a table with the binary bits and what operation it does, so for example if you selected Input A & Input B so they both true and your multiplexer has the AND, NOT & OR gates like they asked in phase 1 and you were to cover up your ALU with a piece of paper on your screen so all you could see was Input A, Input B, the multiplexer input & the result - could someone like me who has no idea what multiplexer input value activates which gate use the table of inputs to select the correct gate to get the expected result?

Hopefully that makes more sense than the assignment instructions.