Which of the following is not a transition element?

Options

A. Mn
B. Fe
C. Cu
D. K

Explanation

To determine which of the following is not a transition element, we need to first understand what transition elements are.

### Step-by-Step Solution:

1. **Definition of Transition Elements**: Transition elements are defined as the d-block elements in the periodic table. They are characterized by the presence of d electrons in their penultimate shell.

2. **Identify the Groups and Periods**: Transition elements are found in groups 3 to 12 of the periodic table, starting from the fourth period (row).

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