Answer : 3. "1844 "
Explanation :

1. Kota was the first princely state of Rajasthan to declare female slaughter illegal. In 1834 AD, Maharaja Bhim Singh of Kota declared female slaughter illegal and banned this practice. This step significantly reduced the practice of female slaughter in Rajasthan.

2. After Kota, Udaipur, Jaipur, Jaisalmer, Bikaner, Jodhpur and other states also declared female slaughter illegal. In 1853 AD, the British government also made a law declaring female slaughter illegal.