Final answer:
Landlords gain rental income from their tenants but may face economic complexities such as price ceilings, which can lead to lower quality housing and reduced maintenance.
Step-by-step explanation:
The income that landlords receive from renting apartments is typically known as rental income. This is the regular payment made by tenants to the landlords in exchange for the use of the landlords' property. However, the economics of rental income are not straightforward. Measures like price ceilings can have unintended consequences for both landlords and tenants. Price ceilings may be intended to make housing more affordable for renters, but they can lead to landlords converting apartments into co-ops and condos or investing less in property maintenance, affecting the quality of housing. The underlying principle here is the classic economic concept of opportunity cost, which implies that if renters pay below-market rates, they might end up with lower-quality housing options due to reduced profitability for landlords.