In oogamy,fertilization involves:

• A
  $A$ small non-motile female gamete and a large motile male gamete.
• B
  $A$ large non-motile female gamete and a small motile male gamete.
• C
  $A$ large non-motile female gamete and a small non-motile male gamete.
• D
  $A$ large motile female gamete and a small non-motile male gamete.