Question: A notable rookie from the 2002 AFL draft was drafted due to which rule?

Context paragraphs:
2001 AFL draft: The 2001 AFL draft consisted of a national draft, a rookie draft, a pre-season draft and a trade period.  The AFL draft is the annual draft of players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League (AFL).

Jobe Watson: Jobe Watson (born 8 February 1985) is a former professional Australian rules footballer who played for the Essendon Football Club in the Australian Football League (AFL).  Watson, the son of three-time Essendon premiership champion and Seven Network commentator Tim Watson, was drafted by Essendon under the father–son rule in the 2002 AFL draft, and went on to become one of the greatest midfielders of the modern era.  A dual All-Australian, three-time W. S. Crichton Medallist and representative of Australia in the 2014 International Rules Series, he captained Essendon between 2010 and 2015, and was the face of the Essendon playing group during the club's most turbulent period in the history of the VFL/AFL.

AFL pre-season draft: The AFL pre-season draft is the drafting of uncontracted players to teams in the Australian Football League.  The draft is conducted after the national AFL draft and before the start of the next AFL season.  It is conducted at the same time as the AFL rookie draft.  The pre-season draft is a place for any uncontracted players to nominate that missed the AFL draft or who were delisted after the main draft.  It was first held in 1989 and has been diminishing greatly in its importance; the last five years have only averaged 8 selections per year, compared to over 50 in each of the first five years.  It was considered that the pre-season draft only existed to protect the league from writs for restraint-of-trade, but due to the introduction of free agency in 2012, there have been calls to scrap the pre-season draft and extend the free agency period.

Dylan Smith (Australian rules footballer): Dylan Smith (born 18 July 1982) is a former Australian rules footballer who played for the Kangaroos and Fremantle in the Australian Football League (AFL).  He grew up in Woodend, approximately 60 km north of Melbourne, and played junior football for the Woodend Junior Football Club.  He left Woodend to take up a scholarship at Hailebury College.  In 1999, he was captain of the Sandringham Dragons who also won the premiership.  He was awarded the medal for the best player on the ground in the grand final.  He was originally drafted by the Kangaroos from Sandringham in the TAC Cup with selection 6 in the 2000 AFL Draft but only played 11 league games for them in three years.  At the end of the 2003 season he was delisted and Fremantle rookie listed him with the 26th selection in the 2004 AFL draft.  He played ten games for Fremantle in the next two years after being elevated to the senior list when Ryley Dunn fractured his collarbone midway through the 2004 season.

AFL Draft Combine: The AFL Draft Combine, formerly known as the AFL Draft Camp, is a gathering of prospective talent, where selected potential draftees display their athletic prowess and relevant Australian rules football skills.  Over four days participants are required to undergo a series of medical, psychomotor, athletic and fitness tests as well as interviews conducted by the 18 clubs in the Australian Football League.  The first AFL Draft Camp was held in 1994 at Wavereley Park, it then moved to Canberra in 1999 where it was hosted by the Australian Institute of Sport, and in 2011 it was moved to Docklands Stadium.  Each year the Draft Combine is held in the following week following the AFL Grand Final.

2005 AFL draft: The 2005 AFL draft was the 2005 instance of the AFL draft, the annual draft of talented players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League. The 2005 draft consisted of a pre-season draft, a national draft, a trade period and a rookie elevation.

Steven Salopek: Steven Salopek (born 21 June 1985) is an Australian rules footballer of Croatian descent who played for Port Adelaide Football Club in the Australian Football League (AFL).  Originally from Narre Warren Football Club in Melbourne's south-east, Salopek played for the Dandenong Stingrays in the TAC Cup before being a first round drafted choice at the 2002 AFL Draft, being selected at number six by Port Adelaide.

1999 AFL draft: The 1999 AFL draft consisted of a pre-season draft, a national draft, a trade period and a rookie elevation.  The AFL draft is the annual draft of talented players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League.

2003 AFL draft: The 2003 AFL draft was the 2003 instance of the AFL draft, the annual draft of talented players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League.  The 2003 draft consisted of a trade period, the national, pre-season and rookie drafts and the elevation of previously drafted rookies to the senior list.

2002 AFL draft: The 2002 AFL draft consisted of a pre-season draft, a national draft, a trade period and the elevation of rookies.  The AFL draft is the annual draft of talented players by Australian rules football teams that participate in the main competition of that sport, the Australian Football League.

Supporting paragraphs: Jobe Watson 2002 AFL draft
Answer: father–son rule