Consider the following fruits :I.PapayaII.PineappleIII.GuavaHow many of the above were introduced in India by the Portuguese in the sixteenth and seventeenth centuries?

1. A

   Only one

   Only one. Papaya, pineapple and guava are all keyed as the tropical-fruit set asked.

2. B

   Only two

   Only two. Under-counts.

3. C

   All the three

   All the three. All three fruits match the stem’s test.

4. D

   None

   None. All three hold.

Summary. Official Set A key is (c) all three. Papaya, pineapple and guava all satisfy the botanical / cultivation test in the question (tropical fruits as printed). None is an extra.