create a custom object and it should have a field which is a lookup relation to Opportunity.  Create one more picklist field is Type__c(Category_A, Category_B, Category_C). three fields should created on Opportunity(Count of CategoryA,Count of CategoryB, Count of CategoryC). display the count of eachtype in the parent details record.

create a custom object and it should have a field which is a lookup relation to Opportunity.  Create one more picklist field is Type__c(Category_A, Category_B, Category_C). three fields should created on Opportunity(Count of CategoryA,Count of CategoryB, Count of CategoryC). display the count of eachtype in the parent details record.