Explanation

Bacillus bacteria:

These are rod-shaped, Gram-positive bacteria that can form endospores. 

Pseudomonas:

These are Gram-negative bacteria, not bacilli. 

Clostridium:

These are also Gram-positive bacteria, but they are anaerobic, unlike most Bacillus species. 

Salmonella:

These are Gram-negative bacteria, not bacilli. 

Streptococcus:

These are Gram-positive cocci (round bacteria), not bacilli.