The correct answer is D. All of these.
Silk yarn reeling units have been set up in private sector in all three districts of Himachal Pradesh: Kangra, Bilaspur, and Mandi.
In Kangra district, there are two silk yarn reeling units, one at Palampur and the other at Dharamshala. The Palampur unit was set up in 1998 and has a capacity of reeling 100 tonnes of silk yarn per annum. The Dharamshala unit was set up in 2002 and has a capacity of reeling 50 tonnes of silk yarn per annum.
In Bilaspur district, there is one silk yarn reeling unit at Hamirpur. The unit was set up in 2005 and has a capacity of reeling 50 tonnes of silk yarn per annum.
In Mandi district, there is one silk yarn reeling unit at Mandi. The unit was set up in 2008 and has a capacity of reeling 50 tonnes of silk yarn per annum.
The setting up of these silk yarn reeling units has helped to boost the silk industry in Himachal Pradesh. The units have provided employment to a large number of people and have also helped to increase the production of silk in the state.