What Could Cause a Sales Volume Variance for Fixed Expenses

What could cause a sales volume variance for fixed expenses?

A) Insurance costs on the factory rise unexpectedly during the year due to a crisis in the insurance industry.
B) The union calls for a strike of factory workers and temporary workers are hired to fill in for the striking employees.
C) The lease on the manufacturing facility is renegotiated and the lease payments increase during the year.
D) The number of units actually sold falls within a different relevant range than the static budget sales volume.