Detailed Answer
Correct answer: (C)
Have a look at ss.29-30 PA 1890.
In the absence of consent from Liam, Daniel is likely to be liable to account to Liam under s.29 PA 1890 for the benefit he has received.
On the bare facts, there is no clear evidence that Car Parts (Garages) Co is a competing business. If it is, then Daniel has been engaged in a competing business without Liam's consent under s.30 PA 1890 and he will be liable to account for all profits made by him in that business. Further information is needed.
Liam has no power to expel Daniel (s.25 PA). If Daniel retires from the firm, Liam acting alone cannot continue as a partner because the definition of partnership will no longer be fulfilled (s.1 PA 1890).