Question

Increasing your 401k deduction will ________ your gross pay and __________your federal taxes in the current year. Decrease, Increase

Answer 1

Increasing your 401k deduction will increase your gross pay and decrease your federal taxes in the current year.

Answer 2

I believe the answer is: Decrease, Decrease

The allocation for 401k deduction would be directly cut from your payment as soon as it arrive. So, the amount of payment for your work would be automatically decreased.
But, the deduction from 401k is not considered as a taxable income, so the payment for your federal tax at the current year would also be decreased.