The individual that Dante does not encounter in Limbo is D) Abraham.
In Inferno, Dante shares a conversation with Virgil, who tells him that he saw Jesus descend into Limbo in order to transport Abraham and other important figures such as Adan and Moses and save their souls. For that reason, Dante does not encounter Abraham in Limbo. However, he finds Ovid within the group of the great poets and he encounters Heraclitus, who is part of the group of philosophers, in Limbo. Moreover, Dante also sees Avicenna, a Persian polymath, during his journey.