Please choose the correct ending to complete the given sentence: Work World: [header] How to become a customs inspector [title] Be a citizen and resident of the united states. [step] Before you can be eligible to work as a customs inspector in the united states, you have to be a u.s. citizen who has lived in the u.s. for at least 3 of the past 5 years. You'll also need a valid driver's license.

Ending1: [title] Make sure you're in the right age range. [step] Us customs and border protection requires that applicants be referred for selection prior to their 40th birthdays. Ending2: Work as a member of the u.s. border patrol (uscis) and for tax purposes. Ending3: [substeps] Under the waiver act of 1965, a u.s. citizen cannot work beyond the age of 40, except for a certain years when he or she is at least 21 years old. Ending4: [substeps] If you're a u.s. citizen, you can't work as a customs inspector without your us citizenship, and you need a voter registration card.

Answer format: ending1/ending2/ending3/ending4