下列判断正整数n是否为质数的Python实现代码中，逻辑完全正确的是？

def is_prime(n):
    for i in range(2, int(n**0.5)+1):
        if n % i == 0:
            return False
    return True

def is_prime(n):
    if n <= 1:
        return False
    for i in range(2, int(n**0.5)):
        if n % i == 0:
            return False
    return True

def is_prime(n):
    if n <= 1:
        return False
    if n == 2:
        return True
    for i in range(2, int(n**0.5)+1):
        if n % i == 0:
            return False
    return True

def is_prime(n):
    if n <= 1 or n % 2 == 0:
        return False
    for i in range(3, int(n**0.5)+1, 2):
        if n % i == 0:
            return False
    return True