Charging by friction is accompanied by loss or gain of electrons. State which body loses electrons when a glass rod is rubbed with silk.

The correct option is A $glassrod$
On rubbing a glass rod with silk, the electrons from the glass rod get transferred to the silk. The silk now has an excess of electrons and so is negatively-charged. On the other hand, the glass rod is deficient in electrons and hence is positively-charged.
In the above example, the silk undergoes negative electrification.
Therefore, in this case of conduction, the glass rod losses it electrons to the silk.