How many sperms are formed by one primary spermatocyte?

One primary spermatocyte (2n) undergoes meiosis I and produces two daughter cells, each of which is known as secondary spermatocyte. 
A secondary spermatocyte (n) then undergoes meiosis II and produces two daughter cells, known as spermatids (n). 
These spermatids undergo spermiogenesis to become sperm (n). Spermiogenesis is a process in which they grow a tail from the centrosome, a midpiece containing several mitochondria which helps in production of ATP, and head, which contains the acrosome and the nucleus containing the haploid set of chromosomes. Hence, 4 sperms are produced from 1 primary spermatocyte. Hence, option A is correct.