Topic: Adverb (ক্রিয়াবিশেষণ),

Best Answer Explained in Below-:

The correct answer to the question "Which of the following word is an adverb?" is **B) Economically**. An adverb is a part of speech that modifies a verb, an adjective, or another adverb, often providing information about how, when, where, or to what extent an action is performed.

Let's analyze the options provided:

- **A) Economic**: This is an adjective that describes something related to economics or the economy, such as "economic growth."

- **B) Economically**: This is an adverb and derives from the adjective "economic." It describes the manner in which something is done concerning efficiency or resource management, as in "She managed the project economically."

- **C) Economical**: Similar to "economic," this is also an adjective that refers to something that is cost-effective or efficient in consumption.

- **D) Economize**: This is a verb that signifies the act of saving resources or reducing expenses.

In summary, **Economically** is the only word in the list that functions as an adverb, modifying actions by indicating how they are executed. This distinction is key in identifying parts of speech correctly.