It is generally accepted that a special feature of the period between 200 B.C. and 300 A.D. is the increase in external trade. Which of the following factors did not assist in the increase?

• A. From a political point of view India had become one.
• B. The Mauryas had constructed various roads and introduced uniform system of administration and this helped in increase in trade.
• C. Indo-Greek rulers helped by establishing close relations with countries of the Mediterranean and West Asia.
• D. The Saka, Parthian and Kuana rulers helped by establishing close ties with Central Asian rulers.