A varicocele is an abnormal enlargement of veins in the pampiniform plexus which may hinder blood flow through the pampiniform venous plexus into the testicular vein. The reduced venous drainage and the resulting elevated testicular temperature may be caused by .
a. defective venous valves in the testis
b. elevated systemic arterial blood pressure
c. elevated core body temperature
d. reduced testicular arterial blood flow

the correct answer is (a) defective venous valves in the testis

Explanation:

Varicocele is found to be caused by defective venous valves in the veins within scrotum.This venous valve is called the pampiniform venous plexus. It is network of small veins, that surrounds each testicular artery.In addition to its function in venous return from the testis,it also plays a role in the thermal regulation of the testis. It reduces the temperature by absorbing heat from the arterial blood, cooling it before it enters testis.

Hence statement (a) is the correct answer.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.