To identify the incorrect pair, we need to understand the classification of different plant types under the division Pteridophyta, which include four classes:

1. Psilopsida: This class includes primitive vascular plants that do not have true leaves or roots. They have simpler structures. A common example is Psilotum.

2. Lycopsida: These are characterized by microphyllous leaves and strobili (cones). An example is Selaginella.

3. Sphenopsida: This class includes plants that have jointed stems and small leaves usually arranged in whorls. An example is Equisetum, rather than Adiantum.

4. Pteropsida: These are the most evolved among pteridophytes and include ferns with large leaves (megaphylls). Examples include Dryopteris, Pteridium, etc.

Now let's analyze each option:

Option A: Sphenopsida – Adiantum

This pair is incorrect. Sphenopsida includes plants like Equisetum, not Adiantum. Adiantum belongs to the class Pteropsida.

Option B: Pteropsida – Dryopteris

This pair is correct. Dryopteris is a type of fern and belongs to the class Pteropsida.

Option C: Psilopsida – Psilotum

This pair is correct. Psilotum is a representative of the class Psilopsida.

Option D: Lycopsida – Selaginella

This pair is correct. Selaginella is a member of the class Lycopsida.

Thus, the incorrect pair is:

Option A: Sphenopsida – Adiantum