In each of the questions given below four words are given in bold. These four words may or may not be in their correct position. The sentence is then followed by options with the correct combination of words that should replace each other in order to make the sentence grammatically and contextually correct. Find the correct combination of the words that should interchange. If the sentence is correct as it is then, select option “No interchange required” as your choice.

The spinster (A) carefully loosened her thread (B) from the spin (C) and began to spool (D) it into a masterpiece.

To determine the correct interchange of words, let us analyze the context and grammatical structure of the sentence:
"The spinster (A) carefully loosened her thread (B) from the spin (C) and began to spool (D) it into a masterpiece."

1. "spinster (A)": A spinster historically refers to a woman who spins thread, or more commonly today, an unmarried woman. In this context of textile making, "spinster" fits grammatically and semantically as the subject performing the action. No change is needed here.

2. "thread (B)": This is a noun representing the strand of fiber. Loosening "her thread" makes perfect grammatical and contextual sense. No change is needed here.

3. "spin (C)" and "spool (D)":
- The phrase "loosened her thread from the..." requires a noun that represents an object from which thread is wound or loosened. A "spool" is a cylindrical device on which thread is wound. Thus, "spool" fits perfectly in position (C).
- The phrase "began to... it into a masterpiece" requires a verb in the infinitive form following "began to". "Spin" is a verb meaning to draw out and twist fibers into yarn or thread. Thus, "spin" fits perfectly in position (D) as "began to spin it into a masterpiece."

By swapping C and D, the sentence becomes:
"The spinster (A) carefully loosened her thread (B) from the spool (C) and began to spin (D) it into a masterpiece."

This is grammatically correct and contextually coherent. Therefore, the words in positions C and D must interchange.

The correct option is C-D.