Final answer:
Christopher should likely use the Qualifying Widower filing status if he has a dependent child, which offers benefits similar to married filing jointly. If he doesn't have a dependent child, his status would be Single. It's important to consult IRS guidelines or a tax professional for specific advice.
Step-by-step explanation:
If Christopher's wife, Sarah, died last year and he has not remarried, the most appropriate filing status for him on his income tax return for this year would generally be Qualifying Widower (if he has a dependent child). This status allows the taxpayer the same standard deduction as a married couple filing jointly and can be used for two years following the year of the spouse's death, provided that the taxpayer does not remarry and maintains a home for a dependent child. However, if he does not have a dependent child, then he would likely file as Single.
It's essential for Christopher to check the specific IRS guidelines or consult with a tax professional to confirm his eligibility as tax laws can have nuanced rules that might affect individual circumstances.