In the following question, the sentence is given with a blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by choosing the appropriate option.\n\n"The shepherd guarded a large ________ of sheep and allowed them to move from pasture to pasture."

Introduction / Context:
This question tests your knowledge of collective nouns in English. Collective nouns are special words used to refer to groups of people, animals, or things as a single unit. In this sentence, you are asked to choose the correct collective noun for a group of sheep. Knowledge of such set expressions is important for both correct grammar and natural sounding usage.

Given Data / Assumptions:

• Sentence: The shepherd guarded a large ________ of sheep and allowed them to move from pasture to pasture.
• Options: block, culture, shoal, flock.
• The subject is a shepherd, and the animals are sheep grazing in pastures.
• We assume the question is about the correct collective noun for sheep.

Concept / Approach:
In English, the standard collective noun for sheep is flock, as in a flock of sheep. This term can also be used for birds such as a flock of geese. Shoal is the collective noun for fish, culture is unrelated to animal groups, and block refers to a solid piece or a city block, not a group of animals. So, the only option that fits both meaning and common usage is flock.

Step-by-Step Solution:
Step 1: Identify that the blank must be filled with a collective noun describing many sheep together. Step 2: Recall that English uses a flock of sheep as the standard phrase. Step 3: Compare this with each option: block of sheep, culture of sheep, shoal of sheep, and flock of sheep. Step 4: Notice that only flock of sheep is idiomatic and widely recognised.

Verification / Alternative check:
Mentally test each option in context: The shepherd guarded a large block of sheep sounds wrong, because block does not refer to groups of animals. Culture of sheep is meaningless in this sense. Shoal of sheep is incorrect because shoal is used for fish, as in a shoal of fish. Flock of sheep, in contrast, is the exact phrase taught in English textbooks and used in everyday speech, confirming that flock is the correct answer.

Why Other Options Are Wrong:
Option A, block, is a word used for solid masses, groups of buildings, or obstruction, but not for animal groups. Option B, culture, refers to shared customs, artistic achievements, or sometimes bacterial growth in science, none of which fits here. Option C, shoal, describes a group of fish or sometimes sandbanks in water; it is not used for sheep. Therefore, all three are semantically inappropriate for this context.

Common Pitfalls:
A learner who is unsure about collective nouns might guess randomly, especially between shoal and flock, because both are used for creatures. It is important to memorise a few high frequency combinations like a herd of cows, a flock of sheep, a shoal of fish, and a pride of lions. These are standard expressions often tested in competitive exams and form part of basic English usage.

Final Answer:
The correct collective noun is flock, so the sentence should read: The shepherd guarded a large flock of sheep and allowed them to move from pasture to pasture.