Which of the following changes are true of the Tax Cut and Jobs Act $($TCJA$)$ of $2017?$

a$.$

Businesses are allowed to immediately deduct $100\%$ of the cost of eligible property in the year it is placed into service through $2022.$

b$.$

Allowable bonus depreciations will phase down over four years.

c$.$

Both A and B are true.

d$.$

None of the above are true.