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

How to use a pay phone
Carry enough coins for a phone call.
Some pay phones-especially those in airports and train stations-also accept credit cards these days, but the charges for those can be extra high. Make sure you read the cost on the machine before paying.

Available choices:
1). Some phones may charge towards the recipient's money card. Consider leaving one free jack on your service phone.
2). Know your minimum phone charges when charging. If you plan to call in cash, find out what the minimum number (4 , 100 canadian pounds) is to call instead of what is included for a credit card (7 , 200 us dollars).
3). If you are planning to make calls in the bathroom, remember to bring coins (around 20 euros worth). For emergencies, you might want to use a us post card or traveler's check instead of a credit card to receive you more coins.
4). Buy a small pack of wet wipes and gently wipe over the phone. You don't know who has used it before you.
The answer is:
4).