In the following question, four words are given. Choose the correctly spelt word that matches the standard English spelling related to the verb “castigate”.

Introduction / Context:
Spelling questions check familiarity with standard written English. The word in focus here is the past tense of the verb “castigate”, which means to criticize severely or punish verbally. Correct spelling is important not only for scoring well in exams but also for writing emails, essays, and reports that look professional and trustworthy.

Given Data / Assumptions:
We are given four spellings: “castegated”, “castigatad”, “castigated”, and “casttigated”. The task is to choose the correct standard spelling of the past tense of “castigate”. We assume modern standard English dictionaries as the reference and that the verb base form “castigate” is known to the learner.

Concept / Approach:
The correct base verb is “castigate”. To form the simple past, we normally add “d” or “ed” to regular verbs. Here, “castigate” ends with “e”, so we simply add “d” to get “castigated”. Therefore, we should look for the option that exactly reflects “castigate” plus “d” with no extra letters or vowel changes.

Step-by-Step Solution:
Step 1: Start from the base verb “castigate”. Step 2: Form the past tense by adding “d”: “castigate” becomes “castigated”. Step 3: Check option (c): “castigated” matches this pattern perfectly. Step 4: Check option (a): “castegated” changes the vowel sequence from “iga” to “ega”, which is incorrect. Step 5: Check option (b): “castigatad” incorrectly uses “ad” instead of “ed” or “d”. Step 6: Check option (d): “casttigated” adds an extra “t”, which does not appear in the base word.

Verification / Alternative check:
If you consult a reliable dictionary or spell checker, you will find the verb forms “castigate, castigates, castigated, castigating”. The spelling stays consistent in all these forms. When reading formal texts such as literary criticism or news commentary, you may encounter sentences like “The editor castigated the journalist for factual errors.” Seeing real usage reinforces that “castigated” is the correct spelling.

Why Other Options Are Wrong:
“Castegated” introduces the letter “e” after “t” in place of the correct “i” structure, which breaks the original spelling of the root word.
“Castigatad” is wrong because English past tense endings are typically “ed” or “d”, not “ad”, unless the base verb itself ends in “a”.
“Casttigated” duplicates the “t”, but the root “castigate” has only one “t”, so adding another letter is unjustified.
These variations are typical misspellings that appear in exams to mislead candidates who only glance quickly at the word.

Common Pitfalls:
One frequent mistake is not recalling the base form and looking only at the ending, which leads students to think “any option ending with -ed must be correct”. Another pitfall is being distracted by letter patterns that look visually familiar, such as the double “t” in “casttigated”. To avoid these mistakes, always mentally reconstruct the base verb or try to use the word in a sentence while checking each letter carefully.

Final Answer:
The correctly spelt word is castigated.