Final answer:
The consideration that was NOT taken into account when choosing tetraethyl lead as an antiknock compound was who was holding the patent on the compound. Tetraethyl lead was widely used as an antiknock compound in gasoline until its use was phased out in 1986 due to health risks.
Step-by-step explanation:
When choosing tetraethyl lead as an antiknock compound, the consideration that was NOT taken into account was who was holding the patent on the compound. The other considerations included its effectiveness as an antiknock compound, the effect on human health, and the cost of production. Tetraethyl lead was widely used as an antiknock compound in gasoline until its use was phased out in 1986 due to the health risks associated with lead exposure.