Final answer:
Causal research is most suitable for Mandy & Co. to determine the effect of advertising on sales, as it looks to establish a cause-and-effect relationship.
Step-by-step explanation:
To assess the influence of advertising on sales at Mandy & Co., the type of research that should be conducted is B. Causal research.
This research method will allow the company to understand if there is a cause-and-effect relationship between the advertising campaigns and sales figures. Causal research is designed to determine whether a change in one variable is responsible for a change in another variable, for example, if the $10,000 advertising campaign caused an increase in sales.
Unlike exploratory or descriptive research, which seek to discover trends, patterns, and provide detailed descriptions respectively, causal research aims to establish a direct linkage. This can be ascertained by potentially conducting controlled experiments or observing variations in sales after applying advertising strategies.