Bacterial infections within the organ where this substance is produced cannot be treated with daptomycin due to daptomycin’s high avidity for this substance. Colfosceril palmitate or Survantra can be used to treat patients whose levels of this substance are critically low. The innate immune properties of this substance are mediated by the collectins SP-A and SP-D. Amniotic fluid is routinely tested for its ratio of lecithin (“LESS-uh-thin”) to sphingomyelin (“sfing-go-MY-uh-lin”) to assess fetal production of this substance. Prematurely born infants are at higher risk of IRDS, in which low levels of this substance can result in atelectasis (“at-uh-LECT-uh-siss”). The most prominent compound present in this substance is the phospholipid DPPC. For 10 points, name this substance that reduces the surface tension of alveoli within the lungs. ■END■ (10[2]0[2])