[QA] It can inferred that in the late 20th century Vietnams tourism

Question:

It can inferred that in the late 20^th century Vietnam’s tourism ______.

• A.
  has never been a spearhead economic industry
• B.
  was not as developed as that in other Asian countries
• C.
  has always been effective and necessary for economy
• D.
  did not need natural conditions or cultural traditions