Christ is the Reason

JESUS CHRIST, Son of God, born in 1 BC (see John 3:16, Math.3: 17)

Peter, James and John
Chosen and Ordained to Melchizedek Priesthood by Jesus Christ around 30AD. (see John 15:16 and Math. 16:19)

Joseph Smith and Oliver Cowdery
Ordained to the office of Elder in the Melchizedek priesthood by Peter, James, and John in late Spring of 1829.
(see D&C 20:2-3 and D&C 27:8,9,12)

David Whitmer, and Martin Harris ordained to the office of Elder in the Melchizedek Priesthood by Joseph Smith and Oliver Cowdery. Along with Oliver, David and Martin become the Three Witnesses of the Book of Mormon, and are specifically set apart to choose and ordain the Twelve on February 14th 1835. (see D&C 18.37 History of the Church, Vol. 2, pp. 187-188; Times and Seasons, Vol. 6 p. 868. BH Roberts Complete History of the Church Century I, volume I, Chapter XXX, especially footnotes 13 and 14, pp. 375-375)

Brigham Young
Ordained to the office of Elder February 14th 1835 by the Three Witnesses

Joseph F. Smith
Ordained to the office of Elder by Brigham Young July 1st 1866

George Albert Smith
Ordained to the office of Elder by Joseph F. Smith October 8th 1903

Winslow Farr Smith
Ordained to the office of Elder by George Albert Smith December 26th 1923

Douglas R. Clawson
Ordained to the office of Elder by Winslow Farr Smith December 6th 1932

Francis Marion Partridge
Ordained to the office of Elder by Douglas Clawson March 1st 1936

Paul Grant Partridge
Ordained to the office of Elder by Francis Marion Partridge January 3rd 1965

Adam Grant Partridge
Ordained to the office of Elder by Paul Grant Partridge November 11th 1997