The correct order to carry out the payroll process is as follows:
Start payroll. The system calls up a country-specific payroll program and performs payroll using the values you entered in the payroll program1.
Check result. You check whether payroll has run correctly, or determine where errors have occurred. If desired, you can obtain a detailed payroll log1.
Exit payroll. You exit the payroll run and set the payroll area to "exit". This locks the payroll area for the current payroll period and prevents any changes to the payroll-relevant data1. References = 1: The Payroll Process | SAP Help Portal

Wage types in SAP HCM Payroll are used to assign payments and deductions as well as to control the payroll program. They are the building blocks of the payroll module and areessential to compensate the employees1. In the case of an hourly wage type, the hourly rate, which should be multiplied by the number of hours performed by the employee, during the payroll run2. Therefore, wage types /001 and /002 can be used to calculate the hourly base rate for salaried employees. References =
https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/e533a9d0e7e547818964b2fd3226924b/953ac2531bb9
https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/21a0a960d9b44ccaa6ac02f87e100f2f/37cade5371874

To import an employee's actual planned working time for each partial period, you need to use the variable ASOLL. This variable contains the planned working time in hours for the current partial period. The system calculates this value based on the work schedule rule and the employment percentage entered in the Planned Working Time infotype (0007). The variable ASOLL is used to determine the partial period factor, which is the ratio of the employee's actual planned working time to the full-time planned working time for the same period. The partial period factor is used to prorate the employee's pay and benefits for the partial period. References = Planned Working Time Infotype (0007), Time Evaluation

In the process of Absence Valuation in SAP HCM Payroll for SAP S/4HANA, the system uses the employee grouping for absence valuation in the Valuation of Absences table (T554C) to select an absence valuation rule. This employee grouping is determined by the operation MODIF A in personnel calculation rule XMOD1. Therefore, MODIF A and the Absence Valuation Rule play an important role in Absence Valuation (v_T554C) in Customizing. References =
https://help.sap.com/docs/r/97b4732247c048ef80ca97c92555e703/2.5.latest/en-US/ae17dd5321e8424de1000000

AMT 0.90: This multiplies the amount of the current wage type by 0.90, effectively reducing it by 10%.
ADDWT*: This adds the reduced wage type amount (along with its number) back to the input table (IT), making it available for subsequent calculations or processing.
Why other options are incorrect:
AMT 0.90 ADDWTI:* The 'I' at the end signifies that the result will be stored in the internal table, but not passed back to the input table (IT) for further processing in the current schema.
AMT 0.10 ADDWT* / AMT 0.10 ADDWTI*:** These would reduce the wage type by only 1%, not
10%.