Which is the topic sentence of the following paragraph? Determining the order of ideas in a paragraph is essential to producing a clear and understandable paragraph. A writer who aimlessly presents ideas the reader will not be very successful in presenting his or her ideas. Topic sentences help writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea. Adding support is key. a) Determining the order of ideas in a paragraph is essential to producing a clear and understandable paragraph. b) Topic sentences help writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea. c) A writer who aimlessly presents ideas the reader will not be very successful in presenting his or her ideas. d) Adding support is key.