Answer:
C. This article argues that there are some interesting similarities between Lincoln's and Kennedy's assassinations.
Step-by-step explanation:
When talking of something in the possessive noun, it is mandatory to indicate the apostrophe s ('s) in the primary noun. So, for the above sentence to be grammatically correct, we will have to add 's to both Lincoln and Kennedy as they comprise of separate persons.
This article argues that there are some interesting similarities between Lincoln's and Kennedy's assassinations.
The addition of the 's in the respective names of the two men indicate their respective assassinations.