This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to stack a washer and dryer
Choose compatible appliances.
Theoretically, you could stack any dryer on top of a washer, as long as it fits. However, you could void the warranties on both appliances by doing this.

Options: 1). Instead, look for washers and dryers that are designed to be stacked together. Usually, this means having a washer and dryer of the same brand. 2). There are many reasons a washer or dryer might come along, including : It's not well-suited to weather. It's not good enough to swim with whenever hot-weather may strike. 3). In such cases, make sure that each appliance is compatible, so that they don't spontaneously break when you clean them together. Install a chain washer if you want compact appliances. 4). Things that are appropriate for a washer and dryer include : Cooling units heat-bearing liners scrubbing brushes wiping pads hoses unfiltered air conditioner Use an oven. If your dryer has a flip-top (or pan-top) cover, rotate it so that the plastic rim rests upside down inside the pan.
The answer is:
1).