Select the most appropriate meaning of the given Idiom:-

Chew the cud 

Ponder over something

The most appropriate meaning of the idiom "chew the cud" is to ponder over something. The idiom comes from the habit of ruminant animals, such as cows and sheep, to regurgitate their food and chew it again. This process allows them to extract more nutrients from their food. In a figurative sense, to chew the cud means to think deeply about something, to mull it over.

The other options are not as accurate descriptions of the meaning of the idiom. Biting hardly on something is not the same as chewing the cud. Chewing of chewing gum is not typically associated with the idiom "chew the cud." At one's service is not typically associated with the idiom "chew the cud."