"Questions relating to the constitution, pattern, nomenclature of posts, cadres, categories, their creation/abolition, prescription of qualifications and other conditions of service including avenues of promotions and criteria to the fulfilled for such promotions pertain to the field of policy is within the exclusive discretion and jurisdiction of the State, subject, of course, to the limitations or restrictions envisaged in the constitution of India and it is not for the statutory tribunals, at any rate, to direct the Government to have a particular method of recruitment of eligibility criteria or avenues of promotion or impose itself by substituting its views for that of the State. Similarly, it is well open and within the competency of the State to change the rules relating to a service and alter or amend and vary by addition/subtraction the qualifications, eligibility criteria and other conditions of service including avenues of promotion, from time to time, as the administrative exigencies may need or necessitate. Likewise, the State by appropriate rules is entitled to amalgamate departments or bifurcate departments