Here The Question Please help!

Astructural difference between the trachea and esophagus that prevents the trachea from collapsing is the presence of: a) smooth muscle b) skeletal muscle c) respiratory cilia d) rings of cartilage

Does anyone have an answer to this question? if so me.

Will treating a viral infection with antibiotics affect the course of the infection? a) no; antibiotics work by inhibiting enzymes specific to bacteria. antibiotics have no effect on eukaryotic or virally encoded enzymes. b) no; antibiotics do not kill viruses because viruses do not have dna or rna. c) yes; antibiotics activate the immune system, and this decreases the severity of the infection. d) yes; antibiotics can prevent viral entry into the cell by binding to host-receptor proteins.