<human>: Here is a goal: When making a homemade hand warmer what is a good material to put in the pouch?

How would you accomplish this goal?

OPTIONS:
- Uncooked rice in the pouch will warm up after 30 secs in the microwave and stay warm for 30 mins.
- Uncooked flour in the pouch will warm up after 30 secs in the microwave and stay warm for 30 mins.
<bot>: Uncooked rice in the pouch will warm up after 30 secs in the microwave and stay warm for 30 mins.