$18)$ Rumours and gr creating a channel oftend to develop throughIrd$-$of$-$mouth,formation if not used actly.How can employees effectively use the grapevine to share upward information to their managers? $(2$ marks$)$How can managers repurpose the grapevine to share downward information to their employees? $(2$ marks$).$How can you increase your credibility in business messages? $(6$