Differences in Tamil dialects can be observed in:

The correct answer is: d) All of the above.

Tamil dialects can be observed in the following ways:

• Vocabulary: Different Tamil dialects have different words for the same thing. For example, the word for “water” is “neer” in Standard Tamil, but it is “vāyiru” in the Madurai dialect.
• Pronunciation: Different Tamil dialects have different ways of pronouncing the same words. For example, the word “water” is pronounced “neer” in Standard Tamil, but it is pronounced “nēr” in the Madurai dialect.
• Grammar: Different Tamil dialects have different grammar rules. For example, the word order in Standard Tamil is subject-verb-object, but it is verb-subject-object in the Madurai dialect.

It is important to note that there is no one “correct” way to speak Tamil. All Tamil dialects are equally valid and should be respected.