With final exams approaching, it's time to __________ and start studying seriously.get in shapeknuckle downarms akimbobend over backwardsNext

The correct phrase to complete the sentence is "knuckle down."

“Knuckle down” is an idiomatic expression that means to begin to work seriously and diligently, especially when preparing for an impending challenge like final exams. The phrase conveys a sense of urgency and commitment to studying or laboring hard, which is exactly the mindset needed as students prepare for significant assessments. Others options like "get in shape" are more closely related to physical fitness, while "bend over backwards" implies making a great effort but not necessarily related to focused studying. "Arms akimbo" refers to a pose with hands on hips and doesn't fit the context of studying. Therefore, "knuckle down" accurately captures the need to concentrate and put in the effort required to succeed in exams.