Questions & Answers about मेरी बहन भी थकी है, इसलिए वह आज घर में आराम करेगी।
Because बहन is a feminine noun in Hindi.
The possessive my changes form to match the gender and number of the noun that follows:
- मेरा = my (for singular masculine nouns)
- मेरी = my (for singular feminine nouns)
- मेरे = my (for plural nouns, and some masculine cases)
So:
- मेरा भाई = my brother
- मेरी बहन = my sister
Since बहन is feminine, मेरी is the correct form.
For the same reason: बहन is feminine.
The adjective tired here comes from थका / थकी / थके, and it agrees with the person being described:
- थका = tired (masculine singular)
- थकी = tired (feminine singular)
- थके = tired (plural, or masculine plural)
So:
- वह थका है = he is tired
- वह थकी है = she is tired
Because the sentence is about my sister, Hindi uses थकी.