In English spelling, four possible forms of a word are given. Select the correctly spelt word from the options below.

Introduction / Context:
This is a straightforward spelling question that asks you to identify the one correctly spelt word from four options. Spelling questions test your familiarity with standard English forms, especially for words that may sound similar or have confusing combinations of vowels and consonants. Here, all four options look somewhat plausible at first glance, so you must rely on your memory of correct spellings or your understanding of word formation patterns in English.

Given Data / Assumptions:

• You are given four spellings: "adendum", "atlantise", "inovate", and "abseiled".
• Exactly one of these words is spelled correctly according to standard English usage.
• The task is to choose the correctly spelt word, not necessarily the most common word in everyday speech.

Concept / Approach:
The correct approach is to examine each word and connect it with any familiar base word. "Abseiled" is the past tense of "abseil", a term often used in climbing, meaning to descend a rock face using a rope. The past tense is formed by adding "ed" to the base word "abseil", giving "abseiled". The other options appear to be modified forms of real words but with incorrect spellings, such as "addendum", "Atlantis", and "innovate". Recognising the correct base words and their standard spellings will guide you to the correct option.

Step-by-Step Solution:
Step 1: Look at "adendum". It seems related to the word "addendum", which refers to an addition at the end of a document. The correct spelling has two d letters and a u: "addendum". So "adendum" is incorrect. Step 2: Look at "atlantise". It appears to be a distorted form of "Atlantis" or "Atlantic". The ending "ise" makes it odd, and there is no standard English word "atlantise" in common usage. So it is incorrect. Step 3: Look at "inovate". This resembles the verb "innovate", which means to introduce something new. The correct spelling has double n: "innovate". So "inovate" is incorrect. Step 4: Look at "abseiled". The base word "abseil" is correctly spelled with "abseil". Adding "ed" to form the past tense produces "abseiled", which matches standard English spelling. Step 5: Conclude that the only correctly spelt word among the four options is "abseiled".

Verification / Alternative check:
You can verify by checking how these words would appear in a good dictionary or by recalling when you might have seen them in printed text. "Addendum" and "innovate" are fairly common academic or professional terms, and both use double consonants that are missing in the options given. "Atlantise" does not match any widely accepted standard word, while "abseiled" clearly matches the known form from mountaineering and adventure sports. This reinforces the conclusion that "abseiled" is correctly spelt.

Why Other Options Are Wrong:
"Adendum" is wrong because it omits one d and the u from "addendum". "Atlantise" is not standard and seems to mix elements of "Atlantis" and the suffix "ise" without forming a recognised word. "Inovate" is incorrect because the correct spelling of the verb is "innovate" with two n letters. Each of these three options contains a spelling error, either by missing letters or by using an incorrect suffix.

Common Pitfalls:
Candidates often rely only on sound and ignore common spelling patterns. For instance, many English words that derive from Latin roots retain double consonants, such as "addition", "innovation", and "address". Forgetting these patterns leads to errors like "adition" or "inovate". When unsure, think about related words and how they are spelt, such as "innovation" for "innovate". This habit helps you eliminate incorrect spellings even if you are not one hundred percent sure of the correct one.

Final Answer:
The correctly spelt word is abseiled.