LATIN The singular dative form of causa is

A. causarum
B. causis
C. causum
D. causae

D. Causae

It specifies that in the Dative section on the Singular label, it's "Causae"

dramatic irony is your answer  

lab rats that ate more artifical sweeter gained more weight than those who ate sugar and they had “lower levels of a hormone called glp-1, which affects how full we feel.”