在执行指数搜索时，为什么我们选择指数的底数为2？

def exponential_search(arr, x):
    n = len(arr)
    
    # 如果x不在数组范围内
    if arr[0] > x or arr[n-1] < x:
        return -1
    
    # 找到范围
    i = 1
    while i < n and arr[i] <= x:
        i *= 2
    
    # 在范围内进行二分查找
    left, right = i // 2, min(i, n - 1)
    while left <= right:
        mid = (left + right) // 2
        if arr[mid] == x:
            return mid
        elif arr[mid] < x:
            left = mid + 1
        else:
            right = mid - 1
    
    return -1

# 示例数组
arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
x = 5
result = exponential_search(arr, x)
print(f"Element {x} is present at index {result}")