Niles and Marsha adopted an infant boy (a U.S. citizen). They paid $14,750 in 2017 for adoption-related expenses. The adoption was finalized in early 2018. Marsha received $3,050 of employer-provided adoption benefits. For question (a), assume that any adoption credit is not limited by modified AGI or by the amount of tax liability. a. What amount of adoption credit, if any, can Niles and Marsha take in 2018? b. Using the information in question (a), assume that their modified AGI was $224,000 in 2018. What amount of adoption credit is allowed in 2018? (Do not round intermediate calculations. Round your final answer to the nearest whole dollar amount.) a. Amount of adoption credit b. Amount of adoption credit