What is age of man on Earth?

The period of Earth's history that began 2.5 billion years ago and ended 542.0 million years ago is known as the Proterozoic. Many of the most exciting events in the history of the Earth and of life occurred during the Proterozoic stable continents first appeared and  a long process taking about a billion years. Also coming from this time are the first abundant fossils of living organisms, mostly bacteria and archaea, but by about 1.8 billion years ago eukaryotic cells appear as fossils too. It is not the age of man. The Mesozoic Era is an interval of geological time from about 252 to 66 million years ago till around 66 million years ago. It is also called the age of reptiles, a phrase introduced by the 19th century paleontologist Gideon Mantell. The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words meaning "entirely recent". Thus, option B is correct.