Final answer:
Elena can claim two exemptions on her taxes: one personal exemption for herself and one dependency exemption for her adopted son, Carlos.
Step-by-step explanation:
The question on how many personal and dependency exemptions Elena should compute for her tax situation falls under the category of taxation, which is a part of business studies. Given that Elena is a U.S. citizen living abroad and has an adopted son who is a non-U.S. citizen, she would likely be eligible for a personal exemption for herself and a dependency exemption for her son, provided that she meets the IRS requirements for claiming a dependent. Thus, the correct answer would be two exemptions: one personal exemption for Elena and one dependency exemption for her adopted son, Carlos.