A seaman may not make an allotment to his __________.

Correct Answer: Option C — mother-in-law

Allotments are legally restricted to specific beneficiaries to ensure the financial support of a seaman's immediate family. Under 46 U.S.C. 10315, authorized allotments include spouses, children, and parents, but do not extend to in-laws, such as a mother-in-law, as they are not considered immediate dependents under this statute.