Best Bets on TV Tonight

"Rx for Survival: A Global Health Challenge" (9 p.m. PBS): This new six-hour documentary series reports that public-health breakthroughs have more than doubled life expectancies in developed countries while impoverished nations remain vulnerable to preventable diseases. The story begins with the work of 19th-century scientists such as Louis Pasteur. Continues at the same time Wednesday and at 10 p.m. Thursday.
"BET Anniversary" (9 p.m. BET): Celebrities gather to help the network celebrate its 25th anniversary with a retrospective and a look ahead. Retiring founder Robert L. Johnson receives special honors during the event taped Wednesday at the Shrine Auditorium in Los Angeles.
"Law & amp; Order: Special Victims Unit" (10 p.m., NBC): This is the strongest cog in producer Dick Wolf's powerful crime franchise. This episode has Benson going undercover to investigate a series of rapes linked to a speed-dating service, and discovering that Mike Jergens is the assailant.