Answer:
The correct answer is c. rod-shaped cells with endospores
Step-by-step explanation:
Most members of family Enterobacteriaceae can appear pink after gram staining due to porous membrane like Zymophilus, Pectinatus etc. Most of them form endospores which is a very tough outer covering formed by cells to resist the adverse condition. Many members of these family resides in intestine of animals and helps in food digestion.
These bacteria comes under phylum Firmicutes and mostly are rod shaped(bacillus). So when most of cells comes out purple the rod shaped cells with endospores indicates that gram stain contains the member of family Enterobacteriaceae.