Which was not a motivation for european exploration in the fifteenth and sixteenth centuries? a. the desire to find a sea route to asia b. intellectual curiosity c. the muslim invasion of spain. d. the promise of riches

NOT a motivation:  The Muslim invasion of Spain.

Muslim incursions into the Iberian Peninsula had happened already back in the 8th century, and Muslim populations controlled the southern portions of Spain and Portugal for many centuries.  "The Reconquista" is the name given to the retaking of the lands by Portugal and Spain, completed in 1492.  Following that, there were efforts to force Muslims to convert to Catholic Christianity if they wished to remain in the land.