The periodic table is an arrangement of elements in rows and periods. The correct answer is option C. Some were discovered and some were synthesized.
In the modern periodic table, elements are arranged in order of increasing atomic numbers.
Most of the elements that were discovered before the 1900s were discovered naturally. After 1900, a few elements that occur naturally but are high radioactive with extremely short half lives have been discovered such as Technetium.
However, in the past 100 years, many elements have been synthesized and added to the periodic table. To synthesize an element means to produce the element in a laboratory by bombarding an existing element with particles such as protons and neutrons.
Learn more: https://brainly.com/question/17170685
