The emergence of local share markets outside London was promoted by______.

A．There aren’t enough cabinets.
B．There is too much noise.
C．Office supplies are taking up space.
D．Some teaching assistants don’t have desks.

A．If they don’t involve any risks.
B．If they produce predictable side effects.
C．When the urgent need for them arises.
D．When tests show that they are relatively safe.