Write plural of/to the following words

Question

Write plural of the following words.
Write plural to the following words.

Which one is the correct answer, and why?

Answer 1

Neither of them are correct, really. The first is closest but is missing an article:

"Write the plural of the following words:"

The reason it sounds off without the article is that you're referring to a specific property of the words (their plural in this case) so the definite article is appropriate. You could, however, also write

"Write plurals of the following words"

But in terms of asking a non-native speaker to do this, you risk introducing some ambiguity in that it's possible to interpret that as meaning some words have more than one plural (which they do, but I don't imagine that's an English 101 topic).

Answer 2

Write the plural of the following words.

You need to use the to define the form you need - 'flowers' is the plural of 'flower'.

Answer 3

Of is far more common and the one you should use.

To indicates an object of a verb, a direction (e.g. where is X pointed) or motion.

So write to X is possible if X is someone that is going to receive what you wrote, e.g. I'm writing a letter to my mother.

Write to X can also mean to physically direct your writing to a specific location X, or stop writing when you reach X, e.g. Write to the top of the page.

It's not common (or very correct, probably), but the above meaning can be used more abstractly to mean "direct your writing so it has the consideration of or impression of X" - e.g. Write to your emotions, not logic.

Plural is a word that describes the form of a single word, so it doesn't make sense to be the target of write, and it's not a location or something that would influence a text. So this is one reason why of is preferred.

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However, there is another way of thinking about it which is at least somewhat valid. Take this sentence, for example:

The counterpart to yin is yang.

There are only two possibilities here, yin and yang and the above sentence is saying yin is the opposite or complement of yang.

If the speaker is considering for the time being that there are only two forms of a word, plural and non-plural, then the above works with the word plural.

The plural to brick is bricks.

or

Write the plural to brick.

However, this requires a context to be established where we only care about two things that are complements. Again, generally you want to use of.

Answer 4

In your examples

Write plural of the following words.
Write plural to the following words.

Of is a better choice since it is possessive, the singular's plural.
To is not correct since you're not asking to transform the word as in

Change these words to their plurals

However a native speaker would more probably say

Write the plural of the following words.
Write the plural for the following words.

The latter being used more often in AmE.