Speak Corporation, a calendar-year, CASH-BASIS taxpayer, sell packages of foreign language lessons to individuals planning to work overseas. In December 2019, it sold and received payment for $600,000 of 24-month lesson packages to be provided evenly through 2020 and 2021. Speak Corporation will recognize the $600,000 of income:

A. all in 2019

B all in 2020

C half in 2020 and half in 2021

D all in 2021

The cash basis of accounting recognizes revenues when cash is received, and expenses when they are paid.