Step-by-step explanation:
1. Clarita's total income =
Adjusted gross income (all from wages) + standard deduction
= $19,600 + $3,000 = $22,600 ( Actual spending is only $3,000 for two children)
According to USA (Pub.503.,)
you exclude or deduct dependent care benefits provided by a dependent care benefit plan, the total amount you exclude or deduct must be less than the dollar limit for qualifying expenses (generally, $3,000 if one qualifying person was cared for or $6,000 if two or more qualifying persons were cared for). (If two or more qualifying persons were cared for, the amount you exclude or deduct will always be less than the dollar limit because the total amount you can exclude or deduct is limited to $5,000.
2.Child and dependent care credit for 2019 is Zero
Because .,According to Income tax rules in USA (pub 501) "the deductions for personal and dependency exemptions for tax years 2018 through 2025 are suspended, and therefore, the amount of the deduction is zero. But in determining whether you may claim a person as a qualifying relative for 2019, the person's gross income must be less than $4,200, not zero."
Here Clarita's gross income is $22,600 ., more than $4,200
and 
, respectively. The total probability of knocking down at most two is thus 
, or 
.