Four words are given. Only one of them is spelt correctly. Choose the correctly spelt word.

Introduction / Context:
Spelling questions assess the learner's familiarity with standard English spellings, especially of words that are slightly uncommon but important in reading and writing. The word tested here is related to the idea of making fortunate discoveries by chance. Recognising its correct spelling helps both in understanding literature and in using the word accurately in essays or articles.

Given Data / Assumptions:

• The options are Serendipty, Serendipity, Serndipity, Sernidipity and Serendepity.
• We assume that one option matches the standard dictionary spelling of the word meaning a happy or beneficial discovery made by accident.
• The target concept is the well known English noun serendipity.

Concept / Approach:
The correct spelling of the word is serendipity, with the sequence s e r e n d i p i t y. Many of the incorrect forms in the options are created by omitting letters, rearranging them or changing vowels. Serendipty omits the second i before t y, Serndipity drops an e, Sernidipity rearranges vowels, and Serendepity substitutes e for i. Careful observation of the internal pattern of vowels and consonants is necessary to identify the correct form.

Step-by-Step Solution:
Step 1: Recall or check mentally the correct pronunciation and spelling of the word serendipity.
Step 2: Compare each option with the expected pattern s e r e n d i p i t y.
Step 3: Observe that option B, Serendipity, matches this pattern exactly.
Step 4: Notice that option A, Serendipty, is missing an i before t y.
Step 5: Note that options C, D and E either miss e or i or change them, making them non standard spellings.

Verification / Alternative check:
We can test by using the word in a sentence: It was pure serendipity that he found the lost document. In printed books, dictionaries and reliable websites, the spelling used is always serendipity. None of the other variants appear as accepted forms. If one has seen the title of the popular film Serendipity or the term in articles about scientific discovery, the correct spelling will be visually familiar. This confirms that option B is the only correct spelling.

Why Other Options Are Wrong:
Option A, Serendipty, drops the i that should come before t y, resulting in a pattern that is not recognised. Option C, Serndipity, omits the second e and compresses the syllables ser and en, again producing a wrong form. Option D, Sernidipity, introduces an i where an e should be and breaks the standard pronunciation. Option E, Serendepity, replaces i with e in the second half of the word, which does not match the usual sound or spelling. Because spelling questions require exact matches to standard forms, none of these incorrect variants can be accepted.

Common Pitfalls:
Words borrowed or coined in English that contain several alternating vowels and consonants can be tricky to spell. Learners sometimes rely only on approximate pronunciation, which may not clearly distinguish between e and i sounds. A good habit is to note unusual or interesting words in a vocabulary notebook and write them several times in example sentences. Visual memory of the whole word shape often becomes a strong guide in multiple choice spelling questions.

Final Answer:
The correctly spelt word is Serendipity.