What word refers to a person who is innocent and straightforward, lacking deceit?

The term "artless" is the most suitable choice as it directly describes a person who is innocent and straightforward, exhibiting a lack of deceit or cunning. When someone is described as artless, it indicates that they possess a natural simplicity and guilelessness, often characterized by a sincere and genuine disposition. This word suggests not only innocence but also a certain charm in their straightforwardness, as they do not employ trickery or manipulation in their interactions.

In contrast, the other options pertain to entirely different concepts. "Apostate" refers to someone who renounces a religious belief or political allegiance, which does not relate to innocence or straightforwardness. "Apotheosis" means the highest point or elevation of something, often used in the context of someone being elevated to divine status, thus lacking any connection to personal characteristics of innocence. "Apogee" denotes the farthest point from the Earth in the orbit of the moon or a satellite, which also bears no relation to the qualities of a person’s character. Therefore, "artless" is the clear choice as it encapsulates the essence of innocence and honesty.