The controlling idea of a paragraph is reflected by --

প্রথম থেকে আসা যাক -Controlling Idea: The controlling idea contains your opinion about the topic. It shows what direction you are going to take in writing about the topic. It helps the reader understand your purpose for writing the paragraph or essay. [University of Victoria - Documents]Controlling Idea and Topic Sentence:Paragraph development begins with the formulation of the controlling idea. This idea directs the paragraph’s development. Often, the controlling idea of a paragraph will appear in the form of a Topic Sentence.Traditionally the topic sentence is the first sentence of the paragraph. In this lead position, it functions to introduce the examples or details which will explain the controlling idea.তবে, Topic Sentence শেষের দিকেও থাকতে পারে। যেখানেই থাকুক না কেন এটা Controlling Idea কে Represent করবে।পাশাপাশি Wren and Martin এর বইতেও একই রকম করে বলা আছে।Sources: University of North Carolina. Writing Center and RIT.Clincher Sentence and Topic Sentence:Clincher Sentence হচ্ছে যে বাক্যটা দিয়ে প্যারাগ্রাফের সকল যুক্তি বা বক্তব্যকে Summarize করে Topic Sentence কে Justify করে লেখা হয়।সংজ্ঞাটা অনেকটা এরকম - "The clincher statement re-states the topic sentence of a paragraph but treats the claim as confirmed rather than hypothesis."