To determine which option is less expensive, we need to calculate the total cost for each option.
Paying for 12 months at one time:
$300 for a year's supply
Paying for 1 month at a time:
$30 per month x 12 months = $360 for a year's supply
Therefore, paying for 12 months at one time is less expensive, as it costs $300 compared to $360 for a year's supply.