Question

Constructive receipt represents the principle that cash basis taxpayers should be taxed on income when it is made available to them without substantial restrictions.

Answer 1

If this is a true or false question, then the answer is definitely true.
This definition you wrote above does indeed refer to constructive receipt. It is used to determine whether a tax payer has received a gross income and whether and when he or she should pay their taxes, as well as to calculate how much they are supposed to pay.