A worker at the local supermarket noticed that during covid, many employees and managers were not following and$/$or respecting the government established guidelines $($i$.$e$.$ washing hands, wearing masks and keeping a two meter distance$).$ The worker in question opted to call the store manager to inform him about these issues. This would be an example of$?$

a$.$

informal communication

b$.$

a rumour

c$.$

voice

d$.$

the chain of command

e$.$

the grapevine