Why are 0.3 micrometer mass median diameter (MMD) size particles used in rating the efficiency of aHEPA filter?a. No infectious agent is smaller than 0.3 micrometer.b. Aerosol photometers cannot detect particles smaller that 0.3 micrometer.c. Filters are only efficient down to 0.3 micrometer.d. Because 0.3 micrometer MMD is the smallest particle that a Laskin nozzle can produce.e. 0.3 micrometer MMD is the most penetrating particle size