rajatvmittal wrote:The ancient Romans piped hot water through the walls and under the floors so as to warm up the rooms.

A. so as to warm up the rooms
B. and so would be able to warm up the rooms
C. to warm the rooms up
D. so that they could warm up the rooms
E. in order that they would warm up the rooms

I chose C.
Reason: - 'to warm' is an infinitive clause representing the purpose of the doing the pipe work.
Also The ancient Romans is the subject of 'to warm'.

Other choices such as D also sounds good but C is concise.

What is your take on it?