At the Same Temperature, Why Are Magmas with High Silica

At the same temperature, why are magmas with high silica contents more viscous?

A) Because high viscosity magma will flow more readily and rhyolites flow the farthest.
B) They are more linked together in chains and nets that are strong enough to resist flow.
C) Any magma with more than 50% silica content is too sticky to flow.
D) The magmas with high silica content are also richer in iron and too dense to flow.