Which of the following is the causative agent for the characteristic ulcus serpens of the cornea?

Ulces serpens is a characteristic hypopyon corneal ulcer caused by Pneumococcus. It has a tendency to creep over the cornea in a serpiginous fashion. It has got a greyish white or yellowish disc near the center of cornea. One edge of the ulcer shows more dense infiltration along which the ulcer spreads. The other side may undergo simultaneous cicatrization and the edges may be covered with fresh epithelium. Organisms causing hypopyon corneal ulcer are: Staphylococci Streptococci Gonococci Moraxella Pseudomonas Pseudomonas pyocyanea Ref: Ophthalmology By A. K. Khurana page 119.