Whenever the NFL's free-agent and trade market open, the 49ers could be busy quarterback shopping. But which signal-caller will they pursue? The list is lengthy — if the bits of speculation, opinion and guesswork from the offseason are to be believed. Here's a look:

Marc Bulger, Ravens

The speculation: NFL Network's Michael Lombardi wrote, "I would fully expect (the 49ers) to make a play for Bulger once the free-agent market opens."

Why it makes sense: Jim Harbaugh's older brother, John, the Ravens' coach, cut Troy Smith in 2010 and went with two quarterbacks: Joe Flacco and Bulger, who signed a one-year, $3.8 million deal. Jim Harbaugh evidently has also parted ways with Troy Smith.

Josh Johnson, Tampa Bay

The speculation: Pro Football Weekly floated a rumor that Harbaugh "could be interested" in the Bucs' backup.

Why it makes sense: Harbaugh coached Johnson, 24, at the University of San Diego and was one of the few coaches to express interest in him out of Oakland Tech. In 2006, Johnson's junior season, Harbaugh termed Johnson college football's best QB.

Kevin Kolb, Eagles

The speculation: ESPN's Adam Schefter wrote "every NFC West team except St. Louis has to consider (Kolb) and deal with the Eagles."

Why it makes sense: Without an obvious franchise QB in the draft, Kolb, 26, is young enough to be a quarterback of the future. In addition, he's spent his first four seasons in a West Coast offense.

Carson Palmer, Bengals

The speculation: Sports Illustrated's Peter King wrote that the Niners, Cardinals and Vikings would be the "leaders in the clubhouse" in the race to trade for Palmer if they didn't draft a QB in the first round or trade for Kolb.

Why it makes sense: Palmer, 31, who had a career-high 157.2 rating in a Week 16 win against the Chargers, still has something left. He grew up in Southern California and his wife was raised in SF.

Matt Hasselbeck, Seahawks

The speculation: Pro Football Weekly wroteof the 49ers' QB shopping, "It appears a far more likely option (than Kolb, for the 49ers) could be ... Hasselbeck ... the Niners' personnel staff is pretty familiar with Hasselbeck's body of work."

Why it makes sense: No other QB on the market is more familiar with the intricacies of the West Coast offense thanHasselbeck, 35, a free agent whohas played in a West Coast system since 2001.

— Eric Branch