Final answer:
Managerial Accounting is the field of accounting that prioritizes relevant information for internal decision making. It helps managers in planning and control processes, differing from Financial Accounting which is more focused on comparability for external users.
Step-by-step explanation:
The field of accounting that focuses on providing relevant information necessary for internal decision making rather than on comparability between firms is Managerial Accounting (Option A). Managerial accounting emphasizes information that is future-oriented and does not necessarily conform to external reporting standards. Its main objective is to assist managers in making informed business decisions, budgeting, and strategic planning.