Explanation:

If someone asks you what planet is closest to Earth, you’ll probably blurt out Venus. That’s a perfectly normal thing to say, but it’s also wrong. Numerous websites and even NASA itself say Venus is our closest planetary neighbor. A new article in Physics Today lays out a more accurate way to determine which planets are closest together. It turns out the averages are highly counterintuitive. Mercury (above) is the closest planet to Earth — in fact, it’s the closest planet to every other planet.
Mercury’s orbit doesn’t take it very far from the sun, but Venus gets much farther away from Earth during its orbit. While it gets closer on occasion, it can be as far away as 1.72 AU. Based on PCM, Mercury is closer to Earth almost 50 percent of the time, with the remainder split between Mars and Venus. Therefore, Mercury is closer. Hence option 1st is correct.