Which of the following is an example of formal communication ?
a. putting a sticky note on your boss's computer
b. grapevine messages
c. the employee handbook
d sending a text message to a co-worker

D). The employee handbook.

Explanation:

Formal communication, as the title, suggests communication for formal purposes like business or authorities. Such communication employs a deliberate use of disciplined, and highly sophisticated language to ensure the efficacy of the message as such communications are bounded with some pre-determined goals and emphasizes on appealing the recipient(so they respond positively).

As per the question, the option that exemplifies formal communication would be 'the employee handbook' as it includes formal details and information regarding the purpose, values, commitment, and goal of the organization. Thus, option D is the correct answer.