Write the next sentence in the following story.

How to keep warm in bed
Wear flannel pajamas.
When it's cold out, it's time to switch up your night clothes. Swap out cotton for some flannel pajamas.

Possible answers:
a). You can buy flannel tops and bottoms, as well as night shirts. Flannel is a great insulator that will help you retain your body heat.
b). Fabrics like goose print, wild yellow, and plaid often make good dry sleepers. If you're prone to a lot of sweatiness, options are loose cotton underwear, striped pajamas, and cotton blankets.
c). Look up your wardrobe for cute winter pajamas, or go for flat-down tucked-down sleepwear. Stay in bed at least 8-12 hours a night, or even more, so that your body will have time to adjust to temperature changes.
d). This is the only way to really stay warm. For comfort, go for a light sweater or thermal button-down shirt.. The answer should be
a).