To determine the least expensive plan, we need to calculate the unit price for each subscription.
Unit price is calculated by dividing the total cost by the number of years:
For the one-year subscription: $29.97 / 1 year = $29.97/year
For the two-year subscription: $45.95 / 2 years = $22.98/year
For the three-year subscription: $74.91 / 3 years = $24.97/year
By comparing the unit prices, we can see that the least expensive plan is the two-year subscription, at $22.98/year.