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

How to do laundry while traveling
Plan ahead.
Part of being able to do laundry on the road is packing accordingly. Pack lighter, wrinkle-resistant clothing that will dry quickly.

Pick from:
1). Pack undergarments and other clothing items that can be hung up for later use. You can always dry your clothes after they've been washed, but washing items after they've been taken out can make folding and drying easier.
2). Avoid items in your bathroom or in boxes. Maybe bring a backpack to carry groceries and laundry.
3). If it will be cold at your destination, dress in layers. You can use lighter garments, and you may not need to wash the outer layers as frequently as the inner ones.
4). If you feel you'll sweat a lot, you can also pack thicker clothes. Buying heavier clothes can also help you stay dry while you're doing your laundry.
The answer is:
3).