If a company have two departments manufacturing and trading, which account will they maintain? 1. Cost Accounting 2. Financial Accounting.

does the trading department have separate management ? does it sell only the company's manufactured products, does it have distributors ...
which one is the profit center for the company ? both of them or only the manufacturing department ? however both costing and manufacturing accounting are important, you can't just have costing accounting for the whole company, however you need to track your cost for pricing and management purpose ...
so I think you need to have both (you can create more than one company in the accounting system then consolidate them, this way you will be able to know each department contribution in the profit)

For manufacturing unit need to follow cost accounting because after follow this you will be able to know the cost price per unit.
This cost price will be transfer for your trading unit & that will be the cost of trading unit.
This unit will trade by adding their mark-up and all others related expense.
Trading unit must have to follow financial accounting to know the business result.

They have to maintain two books of account.1.On manufacturing site for production cost and2.financial for trading

Cost Accounting : for the Manufacturing department Financial Accounting : for the net results from Manufacturing department according to the cost accounting and the Trading department

As the Company is manufacturing the material it will maintain Cost Accouting & as company is doing trading to related or non related item related to manufacturing of the company will need to maintain Financial Accounting

DEFINATELY BOTH DEAR WHAT IS THIS QUESTION

both are mandatory