Which choice completes the text so that it conforms to the convention…

Source Texts

Text

Recent analysis of 1999 OX3—an outer solar system object orbiting the Sun between Jupiter and Neptune—has determined its color to be red, suggesting a rocky composition. Such interpretations are ultimately ______ the object's red coloration may be an incidental effect of radiation, solar wind, or collisions with other objects rather than evidence of its physical makeup.

Which choice completes the text so that it conforms to the conventions of Standard English?

speculative; though

speculative, though.

speculative, though

speculative, though;