Hi there!
Let's do letter B - the nucleus.
Part A - We have selected the nucleus
Part B - It is the powerhouse of the cell. It controls cell functions and stores information long-term.
Part C - In cell y, there are chloroplasts, which means that cell y can perform photosynthesis, while cell x cannot.
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!