Final answer:
The crystals commonly seen in alkaline and neutral urine are Magnesium ammonium phosphate (struvite) stones, which form in the presence of urea-splitting bacteria that lead to less acidic urine.
Step-by-step explanation:
The question "Which of the following crystals is seen commonly in alkaline and neutral urine?" pertains to the types of renal calculi present in urine. The correct answer is C. Magnesium ammonium phosphate, also known as struvite stones. When conditions such as urinary tract infections occur due to urea-splitting bacteria like Proteus mirabilis, the urine's acidity decreases, creating an alkaline environment that favors the formation of struvite crystals. In comparison, calcium oxalate stones are most common but are not specifically associated with alkaline urine. Uric acid stones form in acidic conditions, and cholesterol crystals are rare and not typically influenced by urine pH.