Question: The dipicolinic acid is: 
 Options:  <1> One of the first antibiotics of the quinolones group. <2> A compound characteristic of bacterial endospores. <3> A reserve compound present in the metachromatic corpuscles. <4> An acid polysaccharide present in the wall of Gram positive. <5> One of the amino acids of Gram negative peptidoglycan.
2