The answers are C and D.

The sentence discusses an unusual or distinctive behavior associated with Nikola Tesla.

A. endowments: This term refers to natural abilities or qualities given to someone. It doesn't fit the context of the sentence describing an odd behavior or characteristic of Tesla.

B. passions: Passions typically refer to strong emotions or intense feelings about something. It doesn't convey the idea of an odd behavior or quirk that the sentence is describing.

C. quirks: Quirks are specific, unusual behaviors or traits that an individual may have. Given the context, "quirks" aligns well with the sentence's idea of an unusual behavior related to Nikola Tesla.

D. idiosyncrasies: Idiosyncrasies are peculiar or distinctive features or behaviors of an individual. Similar to "quirks," this word fits the context describing an unusual behavior associated with Tesla.

E. assimilation: Assimilation refers to the process of integrating or absorbing something into a larger whole. It doesn't relate to the description of Tesla's unusual behavior.

F. obsessions: Obsessions refer to strong fixations or preoccupations with certain thoughts or ideas. While Tesla may have had strong interests, the sentence focuses on an odd behavior related to meal calculation, not necessarily an obsessive interest.

Among the options provided, "quirks" (Option C) and "idiosyncrasies" (Option D) best fit the context of describing an unusual behavior associated with Nikola Tesla, specifically his habit of calculating the cubic volume of each meal before eating it. Both words convey the sense of peculiar behaviors or traits that set an individual apart, aligning with the context of the sentence.