Explanation:

Only statements 1&3 are correct.

• Himalayan Yak is endemic to the Tibetan Plateau and the adjacent high-altitude regions.

• Yaks are most comfortable above 14,000 feet. They climb to an elevation of 20,000 feet when foraging and usually don't descend any lower than 12,000 feet.

• The yak-rearing states of India are Arunachal Pradesh, Sikkim, Uttarakhand, Himachal Pradesh and Jammu & Kashmir.

• IUCN Red list status of Himalayan Yak is Vulnerable, further, IUCN considers the wild species of yak under Bos mutus, while the domestic form is considered under Bos grunniens. 

• The countrywide population trend shows that the yak population has been decreasing at an alarming rate. According to a census in 2019, India has some 58,000 yaks – a drop of about 25% from the last livestock census conducted in 2012. 

Hence option 3rd is correct.