Out of the four alternatives, select the correctly spelt superlative form of "frothy".

Introduction / Context:
This question tests correct spelling of the superlative form of the adjective "frothy". "Frothy" is commonly used to describe liquids with many small bubbles, such as "frothy coffee" or "frothy waves". The correct superlative form follows regular spelling rules for adjectives ending in "y".

Given Data / Assumptions:

• Base adjective: "frothy".
• Options: "frothyiest", "frotheist", "frothyeist", "frothiest".
• We assume the required form means "most frothy".

Concept / Approach:
The spelling rule for adjectives ending in consonant + "y" is that when forming the comparative and superlative, the "y" changes to "i" before adding "er" or "est". For example, "happy" becomes "happier" and "happiest". Applying this to "frothy" (f-r-o-t-h-y), we drop the "y", change it to "i" and add "est" to get "frothiest". We also ensure that no extra letters are inserted.

Step-by-Step Solution:
Step 1: Start from the base adjective "frothy".Step 2: Apply the rule: change the final "y" to "i" and add "est". This yields f-r-o-t-h-i-e-s-t, spelled "frothiest".Step 3: Examine option (a) "frothyiest". This incorrectly keeps the "y" and inserts "iest", which does not follow the spelling rule and is redundant.Step 4: Examine option (b) "frotheist". Here the letter "y" has been dropped, but the "i" is placed in a way that distorts the base word and may look like "frothe-ist".Step 5: Examine option (c) "frothyeist". This includes both "y" and "eist", making the spelling overcomplicated and incorrect.Step 6: Examine option (d) "frothiest". This perfectly matches the rule for adjectives ending in "y".

Verification / Alternative check:
Test in a sentence: "This is the frothiest cappuccino I have ever tasted." This looks natural and follows the expected pattern similar to "the happiest child" or "the prettiest view". If we use any of the incorrect options, such as "frothyiest cappuccino", the word looks strange and clearly deviates from standard spelling seen in correct English usage.

Why Other Options Are Wrong:

• "frothyiest": Retains "y" and adds "iest", violating the rule and creating an unnecessary extra letter.
• "frotheist": Distorts the pattern and does not correctly transform the "y" into "i".
• "frothyeist": Combines multiple errors by keeping "y" and inserting an extra "e", leading to an unnatural form.

Common Pitfalls:
Many learners know that "iest" is part of the superlative ending but forget the intermediate step of changing "y" to "i". This leads to forms like "happyest" or "frothyiest". A good way to avoid this mistake is to practise with several examples: funny → funniest, busy → busiest, frothy → frothiest. Seeing the pattern repeated reinforces the correct transformation.

Final Answer:
The correctly spelt superlative form is "frothiest".