The correct answer is: a) Standard Meiteilon.
Standard Meiteilon is the dialect of Manipuri spoken primarily in the Imphal Valley. It is the most widely spoken dialect of Manipuri, and is used in government, education, and the media. Standard Meiteilon is based on the dialect of Imphal, the capital of Manipur.
Bishnupuriya is a dialect of Manipuri spoken in the Bishnupur district of Manipur. It is similar to Standard Meiteilon, but has some differences in vocabulary and pronunciation.
Pangal is a dialect of Manipuri spoken by the Pangal people, who are Muslims of Manipuri origin. It is similar to Standard Meiteilon, but has some differences in vocabulary and pronunciation.
Chiru is a dialect of Manipuri spoken by the Chiru people, who are an ethnic group of Manipur. It is different from Standard Meiteilon in vocabulary, pronunciation, and grammar.