Final answer:
The timeframe considered in horizontal analysis is a given period of time, typically multiple years, to analyze trends and changes in a company's financial performance.
Step-by-step explanation:
The timeframe considered in horizontal analysis is option (c) a given period of time. It involves comparing financial data or performance indicators over a specified period, typically multiple years, to identify trends, patterns, and changes in a company's financial performance. This helps in analyzing the company's growth, efficiency, profitability, and financial stability over time. For example, comparing the revenue, expenses, and net income of a company for the last five years can provide insights into its overall financial performance and any significant changes that have occurred.