Which One or More of the Following Devices Are Used

Multiple Choice

Which one or more of the following devices are used in combination with metered dose inhaler (MDI) therapy to reduce the need for hand-breathing coordination and oropharyngeal impaction of aerosolized drugs?
1) Reservoir devices
2) One-way spacers
3) Valved holding chambers
4) Drying chambers

A) 1 and 3 only
B) 1, 2, and 3 only
C) 3 and 4 only
D) 2, 3, and 4 only