Sandra is the owner of a business where she sells custom coffee mugs online. She regularly collects data on her website, including web traffic, customer orders, and time spent on the site. In January, she changed the supplier for the ceramic used in her mugs, and she also updated the design of her website. Later, in April, she noticed that the number of customer orders decreased since January. Her first reaction is to assume that the new ceramic is not as good, leading to fewer orders.
Which of the following are possible confounding variables in this scenario?

O The color of paint used
O Shipping method
O Time of day
O Sales tax
O Whether customers drink coffee or tea
O New website design
O Seasonal orders / time of year