Until an International Astronomical Union resolution on August 24th, 2

Until an International Astronomical Union resolution on August 24th, 2006, the satellite Pluto was classified as a planet; therefore, scientists were unlikely in considering any object within the Kuiper Belt a planet since any such object to be found being smaller than Pluto.

A. planet; therefore, scientists were unlikely in considering any object within the Kuiper Belt a planet since any such object to be found being

B. planet; therefore, scientists were unlikely to consider any object within the Kuiper Belt a planet since any such object found was

C. planet, scientists were unlikely to consider any object within the Kuiper Belt a planet since any such object found was

D. planet, scientists being unlikely in considering any object within the Kuiper Belt a planet since any such object found was

E. planet, with scientists who were unlikely to consider any object within the Kuiper Belt a planet since any such object found being

There is a 3-2 split between options A, B and C, D and E.
In options A and B, two independent clauses are separated by a semicolon.
In options C, D and E, two independent clauses are joined by comma implying that scientists consideration and its reason is the result of the satellite Pluto classification as a planet. This gives a wrong meaning where cause is in place of reason.

Reverse the second sentence, Since any such object(Pluto) was smaller than pluto, therefore scientists were unlikely to consider any object... a planet. This gives a proper meaning.

Idiom to consider X Y is correct in options B,C and E and in considering X Y is wrong as in options A and D.

Also being is used incorrectly implying continuous tense to past events in options D and E.
Also in option E, with scientists is wrong modifier and who were...... is wordy and in wrong tense due to being.