Concept:
Colonialism often used racist ideologies to justify domination and exploitation of colonized people.
Step 1:
Many colonisers considered non-white populations inferior and uncivilized.
\[
A \text{ is correct}
\]
Step 2:
These racist beliefs helped justify economic exploitation, political domination, and slavery.
Step 3:
Racist theories during colonial times often defended slavery and treated non-white people as inferior.
\[
R \text{ is correct}
\]
Step 4:
The reason directly explains how racist ideologies supported colonial exploitation.
\[
R \text{ correctly explains } A
\]
Step 5:
Therefore, both Assertion and Reason are correct, and Reason correctly explains Assertion.
\[
\boxed{\text{(1) Both (A) and (R) are correct and (R) is the correct explanation of (A)}}
\]